bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Reactions of Alkenes
Authors: Taber Douglass
Published: November 2020

Fabio Doctorovich of the Universidad de Buenos Aires reported (J. Org. Chem. 2008, 73, 5379) that hydroxylamine in the presence of an Fe catalyst reduced alkenes such as 1, but not ketones or esters. Erick Carreira of ETH Zürich developed (Angew. Chem. Int. Ed. 2008, 47, 5758) mild conditions for the hydrochlorination of mono-, di- and trisubstituted alkenes. Ramgopal Bhattacharyya of Jadavpur University established (Tetrahedron Lett. 2008, 49, 6205) a simple Mo-catalyzed protocol for alkene epoxidation. Nitro alkenes are of increasing importance as acceptors for enantioselective organocatalyzed carbon-carbon bond formation. Matthias Beller of the Universität Rostock found (Adv. Synth. Cat. 2008, 350, 2493) that an alkene such as 7 was readily converted to the corresponding nitroalkene 8 by exposure to of NO gas. The reaction could also be effected with NaNO2/HOAC. Two complementary protocols for Rh-catalyzed alkene hydroformylation have been reported. Xumu Zhang of Rutgers University devised (Organic Lett. 2008, 10, 3469) a ligand system that cleanly migrated the alkene of 9, then terminally hydroformylated the resulting monosubstituted alkene, to give 10. Kian L. Tan of Boston College designed (J. Am. Chem. Soc. 2008, 130, 9210) a ligand such that the hydroformylation of the internal alkene of 11 was directed to the end of the alkene proximal to the directing OH, delivering 12. Several other methods for the functionalizing homologation of alkenes have been put forward. Chul-Ho Jun of Yonsei University assembled (J. Org. Chem. 2008, 73, 5598) a Rh catalyst that effected the oxidative acylation of a terminal alkene 13 with a primary benzylic alcohol, to give the ketone 14. For now, this approach is limited to less expensive alkenes, as the alkene, used in excess, is the reductant in the reaction. The other procedures outlined here require only stoichiometric alkene. Yasuhiro Shiraishi of Osaka University devised (Organic Lett. 2008, 10, 3117) a simple photoprocess for adding acetone to a terminal alkene 13 to give the methyl ketone 14, in what is presumably a free radical reaction.
Advances in Alkene and Alkyne Metathesis
Authors: Taber Douglass
Published: November 2020

As alkene metathesis is extended to more and more challenging substrates, improved catalysts and solvents are required. Robert H. Grubbs of Caltech developed (Organic Lett. 2008, 10, 441) the diisopropyl complex 1, that efﬁciently formed the trisubstituted alkene 6 by cross metathesis of 4 with 5. Hervé Clavier and Stephen P. Nolan of ICIQ, Tarragona, and Marc Mauduit of ENSC Rennes found (J. Org. Chem. 2008, 73, 4225) that after cyclization of 7 with the complex 2b, simple ﬁltration of the reaction mixture through silica gel delivered the product 8 containing only 5.5 ppm Ru. The merit of CH2Cl2 as a solvent for alkene metathesis is that the catalysts (e.g. 1 - 3) are very stable. Claire S. Adjiman of Imperial College and Paul C. Taylor of the University of Warwick established (Chem. Commun. 2008, 2806) that although the second generation Grubbs catalyst 3 is not as stable in acetic acid, for the cyclization of 9 to 10 it is a much more active catalyst in acetic acid than in CH2Cl2 . Bruce H. Lipshutz of the University of California, Santa Barbara observed (Adv. Synth. Cat . 2008, 350, 953) that even water could serve as the reaction solvent for the challenging cyclization of 11 to 12, so long as the solubility- enhancing amphiphile PTS was included. Ernesto G. Mata of the Universidad Nacional de Rosario explored (J. Org. Chem. 2008, 73, 2024) resin isolation to optimize cross-metathesis, finding that the acrylate 13 worked particularly well. Karol Grela of the Polish Academy of Sciences, Warsaw optimized (Chem. Commun. 2008, 2468) cross-metathesis with a halogenated alkene 16. Jean-Marc Campagne of ENSC Montpellier extended (J. Am. Chem. Soc. 2008, 130, 1562) ring-closing metathesis to enynes such as 19. The product diene 20 was a reactive Diels-Alder dienophile. István E. Markó of the Université Catholique de Louvain applied (Tetrahedron Lett. 2008, 49, 1523) the known (OHL 20070122) ring-closing metathesis of enol ethers to the cyclization of the Tebbe product from 23. The ether 24 was oxidized directly to the lactone 25.
Alkene and Alkyne Metathesis: Phaseolinic Acid (Selvakumar), Methyl 7-Dihydro-trioxacarcinoside B (Koert), Arglabin (Reiser) and Amphidinolide V (Fürstner)
Authors: Taber Douglass
Published: November 2020

As N. Selvakumar of Dr. Reddy’s Laboratories, Ltd., Hyderabad approached (Tetrahedron Lett. 2007, 48, 2021) the synthesis of phaseolinic acid 6, there was some concern about the projected cyclization of 2 to 3, as this would involve the coupling of two electron-deﬁcient alkenes. In fact, the Ru-mediated ring-closing metathesis proceeded efﬁciently. The product unsaturated lactone 3 could be reduced selectively to either the trans product 4 or the cis product 5. There has been relatively little work on the synthesis of the higher branched sugars, such as the octalose 13, a component of several natural products. The synthesis of 13 (Organic Lett. 2007, 9, 4777) by Ulrich Koert of the Philipps-University Marburg also began with a Baylis-Hillman product, the easily-resolved secondary alcohol 8. As had been observed in other contexts, cyclization of the protected allylic alcohol 9a failed, but cyclization of the free alcohol 9b proceeded smoothly. V-directed epoxidation then set the relative configuration of the stereogenic centers on the ring. Ring-closing metathesis to construct tetrasubstituted alkenes has been a challenge, and specially-designed Ru complexes have been put forward specifically for this transformation. Oliver Reiser of the Universität Regensburg was pleased to observe (Angew. Chem. Int. Ed. 2007, 46, 6361) that the second-generation Grubbs catalyst itself worked well for the cyclization of 17 to 18. Again in this synthesis, catalytic V was used to direct the relative configuration of the epoxide. Intramolecular alkyne metathesis is now well-established as a robust and useful method for organic synthesis. It was also known that Ru-mediated metathesis of an alkyne with ethylene could lead to the diene. The question facing (Angew. Chem. Int. Ed . 2007, 46, 5545) Alois Fürstner of the Max-Planck-Institut, Mülheim was whether these transformations could be carried out on the very delicate epoxy alkene 21. In fact, the transformations of 21 to 22 and of 22 to 23 proceeded well, setting the stage for the total synthesis of Amphidinolide V 25.
Enantioselective Assembly of Alkylated Stereogenic Centers
Authors: Taber Douglass
Published: November 2020

Oxygenated secondary stereogenic centers are readily available. There is a limited range of carbon nucleophiles that will displace a secondary leaving group in high yield with clean inversion. Teruaki Mukaiyama of the Kitasato Institute has described (Chem. Lett. 2007, 36, 2) an elegant addition to this list. Phosphinites such as 1 are easily prepared from the corresponding alcohols. Quinone oxidation in the presence of a nucleophile led via efﬁcient displacement to the coupled product 2. The sulfone could be reduced with SmI2 to give 3. Enantioselective reduction of trisubstituted alkenes is also a powerful method for establishing alkylated stereogenic centers. Juan C. Carretero of the Universidad Autonoma de Madrid has found (Angew. Chem. Int. Ed. 2007, 46, 3329) that the enantioselective reduction of unsaturated pyridyl sulfones such as 4 was directed by the sulfone, so the other geometric isomer of 4 gave the opposite enantiomer of 5. The protected hydroxy sulfone 5 is a versatile chiral building block. Samuel H. Gellman of the University of Wisconsin has reported (J. Am. Chem. Soc. 2007, 129, 6050) an improved procedure for the aminomethylation of aldehydes. L-Proline-catalyzed condensation with the matched α-methyl benzylamine derivavative 7 gave the aldehyde, which was immediately reduced to the alcohol 8 to avoid racemization. The amino alcohol 8 was easily separated in diastereomerically-pure form. In the past, aldehydes have been efficiently α-alkylated using two-electron chemistry. David W. C. Macmillan of Princeton University has developed (Science 2007, 316, 582; J. Am. Chem. Soc. 2007, 129, 7004) a one-electron alternative. The organocatalyst 9 formed an imine with the aldehyde. One-electron oxidation led to an α-radical, which was trapped by the allyl silane (or, not pictured, a silyl enol ether) leading to the α-alkylated aldehyde 10. This is mechnistically related to the work reported independently by Mukund P. Sibi (J. Am. Chem. Soc. 2007, 129, 4124; OHL Feb. 11, 2008) on one-electron α-oxygenation of aldehydes. Secondary alkylated centers can also be prepared by SN2’ alkylation of prochiral substrates such as 11. Ben L. Feringa of the University of Groningen has shown (J. Org. Chem. 2007, 72, 2558) that the displacement proceeded with high ee even with conventional Grignard reagents.
Enantioselective Construction of Alkylated Stereogenic Centers
Authors: Taber Douglass
Published: November 2020

The enantioselectivity of alkene reduction usually depends on the geometric purity of the alkene. Bruce H. Lipshutz of the University of California, Santa Barbara used ( Organic Lett. 2007, 9, 4713) carboalumination of the alkyne 1 to prepare 2, which was selectively reduced to 3 in high ee. André B. Charette of the Université de Montréal reported ( Angew. Chem. Int. Ed. 2007, 46, 5955) a related reduction of unsaturated sulfones such as 4. Juan C. Carretero of the Universidad Autónoma de Madrid has developed ( J. Org. Chem. 2007, 72, 9924) a complementary route to enantiomerically-enriched sulfones, by conjugate addition to the unsaturated pyridyl sulfone 6 . Specifically for styrene derivatives, Hans-Günther Schmalz of the University of Cologne has shown (Organic Lett. 2007, 9, 3555) that the product 11 from enantioselective Rh-catalyzed hydroboration can be homologated to 13. Conjugate addition of stabilized carbanions can also be carried out with high enantiocontrol. David A. Evans of Harvard University has described (J. Am. Chem. Soc. 2007, 129, 11583) the Ni-catalyzed addition of malonate 15 to nitroalkenes such as 14. Claudio Palomo of the Universidad de País Vasco (Angew. Chem. Int. Ed. 2007, 46, 8431) and concurrently Yujiro Hayashi of the Tokyo University of Science (Organic Lett. 2007, 9, 5307) have developed organocatalytic protocols for the addition of nitromethane 18 to unsaturated aldehydes such as 17. J. Michael Chong of the University of Waterloo has found (J. Am. Chem. Soc. 2007, 129, 4908) that the Binol-mediated enantioselective conjugate addition of alkenylboronic acids such as 22 required the additional activation of the aryl ketone. Shun-Jun Li of Suzhou University and Teck-Peng Loh of Nanyang Technical University have extended (J. Am. Chem. Soc. 2007, 129, 276) enantioselective conjugate to unsaturated esters such as 24 to more highly substituted Grignard reagents. Alexandre Alexakis of the University of Geneva has demonstrated (Tetrahedron Lett. 2007, 48, 7408) that Ac2O is compatible with Et2 Zn conjugate addition conditions, leading directly to the trapped enolate 27. Selective cleavage of 27 can then be used to prepare acyclic derivatives.
Stereocontrolled Construction of Arrays of Stereogenic Centers
Authors: Taber Douglass
Published: November 2020

Complex natural products and even some complex pharmaceuticals contain arrays of stereogenic centers. Sometimes, the desired array is readily available from a natural product, but usually, such arrays of multiple stereogenic centers must be assembled. Armando Córdova of Stockholm University has reported (Angew. Chem. Int. Ed. 2007, 46, 778) a simple procedure for the organocatalyst-mediated addition of the nitrene equivalent 2 to an α, β-unsaturated aldehyde to give the protected aziridine 4 in high ee. Organocatalysis was also used (Organic Lett. 2007, 9, 1001) by Arumugam Sudalai of the National Chemical Laboratory, Pune, to effect coupling of the aldehyde 5 with dibenzylazodicarboxylate 6 to give, following the List procedure, the intermediate aldehyde 7. Osmylation of the derived unsaturated ester 8 proceeded with high diastereocontrol, to give 9. Products 4 and 9 have adjacent stereogenic centers. Hisashi Yamamoto of the University of Chicago has introduced (J. Am. Chem. Soc. 2007, 129, 2762) the linchpin reagent acetaldehyde “super”silyl enol ether 11. Diastereoselective addition of 11 to the enantiomerically-pure aldehyde 10, with concomitant silyl transfer, followed by the addition of allyl magnesium bromide delivered the protected triol 12 in high de and ee. Arrays that combine alkylated and oxygenated or aminated centers are also important. Akio Kamimura of Yamaguchi University took (J. Org. Chem. 2007, 72, 3569) a Baylis- Hillman like approach, adding thiophenoxide to t -butyl acrylate in the presence of an enantiomerically-pure aldehyde N-sulfinimine such as 13 to give the adduct 14 with high diastereocontrol. Keiji Maruoka of Kyoto University has designed (Angew. Chem. Int. Ed. 2007, 46, 1738) the chiral amine 17, that catalyzed the condensation of an aldehyde with ethyl glyoxylate 16 with high enantiocontrol. In a very thoughtful approach, Liu-Zhu Gong of the University of Science and Technology of China in Hefei extended (Chem. Commun. 2007, 736) the now-classic aldol condensation of cyclohexanone to 4-substituted cyclohexanones such as 19. The product 21 could be carried in many directions, including to the Bayer-Villiger product 22. Arrays of alkylated and polyalkylated centers have been among the most challenging to prepare.
Transition Metal-Mediated C-C Ring Construction: The Stoltz Synthesis of (-)-Cyanthiwigin F
Authors: Taber Douglass
Published: November 2020

X. Peter Zhang of the University of South Florida extended (Organic Lett. 2009, 11, 2273) Co-catalyzed asymmetric cyclopropanation to the activated ester 2. The product 3 readily coupled with amines. André B. Charette of the Université de Montréal showed (J. Am. Chem. Soc. 2009, 131, 6970) that even α-olefins such as 4 could be cyclopropanated in high ee with the diazo amide 5. Xue-Long Hou of the Shanghai Institute of Organic Chemistry established (J. Am. Chem. Soc. 2009, 131, 8734) conditions for the enantioselective coupling of 7 and 8 to give 9 , in which sidechain chirality was also controlled. Tristan H. Lambert of Columbia University found (J. Am. Chem. Soc. 2009, 131, 7536) that “methylene” could be transferred in an intramolecular sense from the epoxide of 10 to the alkene, delivering the cyclopropane 11 in high ee. Yuichi Kobayashi of the Tokyo Institute of Technology established (Organic Lett . 2009, 11, 1103) that the 2-picolinoxy leaving group worked well for the SN2' coupling with 13 to give 14. Chang Ho Oh of Hanyang University developed (J. Org. Chem. 2009, 74, 370) a new route to cyclopentenones such as 16, by gold-catalyzed cyclization of diynes such as 15. David J. Procter of the University of Manchester used (J. Am. Chem. Soc. 2009, 131, 7214; Tetrahedron Lett . 2009, 50, 3224) SmI2 to cyclize 17 to 18 and 19 to 20, each with high diastereocontrol. Yoshiaki Nishibayashi of the University of Tokyo devised (Angew. Chem. Int. Ed. 2009, 48, 2534) Ru catalysts for the cyclization of an enyne such as 21 to the cyclohexadiene 22. Laurel L. Schafer of the University of British Columbia developed (J. Am. Chem. Soc. 2009, 131, 2116) a Zr catalyst for the diastereocontrolled cyclization of amino alkenes such as 23. Hongbin Zhai of the Shangahi Institute of Organic Chemistry showed (J. Org. Chem. 2009, 74, 2592) that the Mo-mediated cyclization of 25 also proceeded with high diastereocontrol. Even more impressive was the selectivity Kozo Shishido of the University of Tokushima demonstrated (Tetrahedron Lett . 2009, 50, 1279) for the cyclization of 27.
The Rychnovsky Synthesis of Leucascandrolide A
Authors: Taber Douglass
Published: November 2020

The macrolactone leucascandrolide A 4, isolated from the calcareous sponge L. caveolata, has both cytotoxic and antifungal activity. The key step in the synthesis of 4 reported (J. Org. Chem. 2007, 72, 5784) by Scott D. Rychnovsky of the University of California, Irvine, was the stereoselective condensation of the aldehyde 1 with the allyl vinyl ether 2 to give 3. The cyclic ether of 1 was assembled from the crotyl addition product 5. Tandem Ru-catalyzed metathesis/hydrogenation converted 5 to the lactone 6. Reduction of 6 to the lactol followed by activation as the acetate gave 7, axial-selective condensation of which with the enol ether 8 delivered the enone 9. Diastereoselective Itsuno-Corey reduction of 9 followed by protecting group exchange and oxidation then gave 1, containing four of the eight stereogenic centers of leucascandrolide A 4. The vinyl ether 2 was readily prepared from the corresponding homoallylic alcohol. Condensation of 1 with 2 involved Lewis acid activation of the aldehyde, addition of the resulting carbocation to the vinyl ether, and cyclization with trapping by bromide ion. In this process, the other four of the eight stereogenic centers were assembled. Three of those centers were formed in the course of the reaction. While stereocontrol was not perfect, the route is pleasingly succinct, so practical quantities of diastereomerically pure 3 could be prepared. To complete the synthesis, the secondary alcohol of 3 was methylated. Selective desilyation of the primary alcohol followed by oxidation and desilylation then set the stage for the Mitsunobu macrolactonization. The intermediates in the Mitsunobu reaction are such that the lactonization can proceed with either inversion of absolute configuration at the secondary center, or retention. While the usually-employed Ph3P gave the lactone with retention of absolute configuration, Bu3P led to clean inversion. The last challenge was the establishment of the (Z) alkene of the side chain. This was accomplished using the Toru protocol. Coupling of the secondary bromide with the Cs salt 12 proceeded with inversion of absolute configuration, to give 13.
The Ley Synthesis of Rapamycin
Authors: Taber Douglass
Published: November 2020

Rapamycin 3 is used clinically as an immunosuppressive agent. The synthesis of 3 ( Angew. Chem. Int. Ed. 2007, 46, 591) by Steven V. Ley of the University of Cambridge was based on the assembly and subsequent coupling of the iododiene 1 and the stannyl alkene 2. The lactone of 1 was prepared by Fe-mediated cyclocarbonylation of the alkenyl epoxide 5, following the protocol developed in the Ley group. The cyclohexane of 2 was constructed by SnCl4 -mediated cyclization of the allyl stannane 9, again employing a procedure developed in the Ley group. Hydroboration delivered the aldehyde 11, which was crotylated with 12, following the H. C. Brown method. The alcohol so produced (not illustrated) was used to direct the diastereoselectivity of epoxidation, then removed, to give 13. Coupling with 14 then led to 2. Combination of 1 with 2 led to 15, which was condensed with catechol to give the macrocycle 16. Exposure of 16 to base effected Dieckmann cyclization, to deliver the ringcontracted macrolactone 17, which was carried on to (-)-rapamycin 3.
The Kobayashi Synthesis of (-)-Norzoanthamine
Authors: Taber Douglass
Published: November 2020

The Zoanthus alkaloids, exemplified by (-)-norzoanthamine 3a and zoanthamine 3b, show promising activity against osteoporosis. Susumu Kobayashi of the Tokyo University of Science assembled (Angew. Chem. Int. Ed. 2009, 48, 1400; Angew. Chem. Int. Ed. 2009, 48, 1404) the challenging tricyclic core of 3a employing the intramolecular Diels-Alder cyclization of 1 to 2. The cyclopentane of 1 served as useful scaffolding, even though it was cleaved en route to 3a. The cyclohexane ring of 1 has five of its six positions substituted, including three that are alkylated quaternary centers. The starting point for the preparation of 1 was the enantiomerically-pure Hajos-Parrish ketone 4, containing the first of the those quaternary centers. Conjugate addition of MeLi established the second quaternary center. The less stable endo alkyl branch of 1 was installed by conjugate addition to the more reactive α-methylene ketone of the cross-conjugated 5, followed by kinetic quench. Addition of vinyl cuprate across the open face of the enone 7 then established the final quaternary center, setting the stage for the intramolecular Diels-Alder reaction. The silyl enol ether from the cyclization of 1 was not stable, so it was directly oxidized to the enone 2. The keto phosphonate 16 for the last two rings of 3a was prepared from the previously-reported crystalline glutamic acid-derived mesylate 12. Reduction and homologation delivered the ester 14, that was condensed with the phosphonate anion 15 to give 16. The congested cyclopentanone 17, derived from 2, was most efficiently deprotonated with n -BuLi. Exposure of the resulting silyl enol ether to ozone led to the α-hydroxylated product 18. Unexpectedly but happily, oxidative cleavage of 18 delivered, after deprotection and reprotection, the more congested aldehyde 19. This cleavage may be proceeding by tautomerization of 18 to the regioisomeric keto alcohol. The aldehyde 19 was condensed with the keto phosphonate 16, to give, after hydrogenation, the keto lactone 20. A series of oxidation state adjustments then completed the synthesis of (-)-norzoanthamine 3a.
Padre Mike and NAFTA Man
Authors: Broughton Chad
Published: November 2020

Mike Allen’s Path to global dealmaker was a strange one. He graduated from Oblate College in San Antonio and was ordained a Catholic priest in 1964. As an oblate in the church, Allen committed his early adult years to the lives of migrant workers and others on the margins, and he considered himself a socialist. He lived in a grungy trailer near the impoverished members of his McAllen parish, where he was known as “Padre Mike.” Not unlike Ed Krueger, Allen worked with the United Farm Workers, taught his parishio­ners how to work the welfare system, and railed against the injustices of capitalism. He had a friendly relationship with Krueger during those years. When Krueger needed something mimeographed, for example, he would go to the office where Allen worked to use his machine. In 1974 Mike Allen left the priesthood and became that most diehard of capitalists: the convert. As he tells it, he evolved, realizing that handouts cannot offer the dignity of work. He took a job working with the Texas Office of Economic Opportunity, where he lobbied in D.C. to get money for Texas and handled economic development grants for Texas businesses. In the mid-1980s he started a company that sold corrugated cardboard to Mexico, invested in a shoe-making maquiladora, and did various consultancies. Then in 1987 Allen moved back to the Magic Valley to lead the McAllen Economic Development Corporation (MEDC) at Mayor Brand's invitation. He was the perfect choice; he felt as comfortable with a Mexican developer or impoverished colonia (neighborhood) dweller as he did with corporate executives or Austin politicos. He wasn’t only bilingual, he was bicultural—and persuasive to boot. In 1988, a year into his tenure at MEDC, Allen met with the mayor of Reynosa, Tamaulipas. A gritty border city of a few hundred thousand, Reynosa lagged behind Tijuana, Ciudad Juárez, and Matamoros, but had been relatively self-sufficient—supported for several decades by its petroleum and natural gas reserves.
Frogs, Mules, and Life after Maytag
Authors: Broughton Chad
Published: November 2020

It Was a cold evening in early December 2006, and Tracy Warner had just returned home from Willits Primary School. Ryan had just sung in the “Winter Wonderland” musical there. Christmas lights dotted F Street, adding some warmth to her modest block in the heart of Monmouth, Illinois. She looked like a new woman, and, judging by her smile, she knew it. The jeans and T-shirt—the uniform of the anxious, soon-to-be-unemployed line worker and picketer of a couple years earlier—had been replaced by a red V-neck sweater, silk blouse, and an aura of confidence. She was wrapping up four fall semester classes and a journalism internship at the school’s news­paper, the Western Courier. She had done this while raising Ryan and frantically looking for a job. She was set to graduate on the following Saturday from Western Illinois University. The dream Warner had dreamt a thousand times while piecing together refrigerator doors on the Maytag line for over fifteen years was coming true. “Look at this,” she said, handing me an essay. “It’s a paper on Rawls’ theory of justice. He said that we have to stand behind a veil of ignorance to make fair decisions.” Her reference fit the moment. John Rawls’ 1971 Theory of Justice poses a hypothetical world in which all societal roles are shuffled behind a metaphorical “veil of ignorance.” Behind this veil, one does not know to what role he or she will be assigned in the new social order. It is only from there, Rawls argues, can one truly judge the fairness of various social roles and relations. The CEO, for instance, would have to experience the lives of workers he put out of work. Warner still saw Ralph Hake as a great villain—and it was not just because of the factory closing and the gutting of her working life as well as the working lives of her friends and co-workers. Warner had embraced the changes as best she could, and she and Ryan would find a way to survive.
“Esa es Mi Visión”
Authors: Broughton Chad
Published: November 2020

Laura Flora Oliveros woke at 5 a.m. and used water in a plastic tub to wash off. She then ate toast and drank watery coffee before leaving around 6 a.m. to make her 7 a.m. shift. On the micro, maquila workers, most of them in their 20s and 30s, usually kept to themselves as they headed to the factories. Sometimes Flora sold manualidades (handicrafts), like the vibrant carrot-orange crocheted dress she had recently finished, on the bus to work. She made them on her day off, Sunday, and had been teaching Laura Suarez how to embroider a tortilla warmer. She also sold lotions and perfumes for JAFRA—a multilevel marketing company along the lines of Amway—to other women on the assembly line. By 2007 a three-year veteran of Planta Maytag III, Flora continued to believe that her girls had a better chance in Reynosa than in Tierra Blanca. In any case, there was no looking back. Production had recently intensified at the refrigerator factory. They were working on a big order to ship across the Rio Grande to Home Depot. The feeling in the plant was one of utter exhaustion, Flora said. They had been producing mountains of scrap as a result. By this point Flora despised Maytag, but she hated scrap more. It was demoralizing, a sign of a collective failure. The Mexican refrigerator makers felt the same weird devotion to production that Galesburg workers displayed even in the final days of production there. At the end of good days, days when the lines ran continuously and little scrap was produced, they’d congratulate one another and go home a little happier. For weeks Flora had often been on her feet until 7:45 p.m. in steel-toed shoes, performing the same tasks over and over again. She had learned thirteen jobs at Planta III, all of them tedious, some of them hard. Overtime bonuses, her paystubs revealed, inflated her average hourly take-home pay to as high as $1.80 an hour, though it was more typical for her to earn around $1.35 in 2007.
Looking North from Barra de Cazones
Authors: Broughton Chad
Published: November 2020

In Barra De Cazones, Veracruz, we ordered Modelos at an empty beach­front restaurant, La Palapa de Kime, on a muggy July afternoon. A handful of vacationers were scattered on the expansive, pebbled, brown sand beach. This was not the tropical paradise of Cabo San Lucas brochures—with expensive hotels and fine white sands—but the scarcity of tourists in this beautiful and serene Gulf Coast village was puzzling at first glance. The roads into town are good—pleasant, twisting runs through a remote and picturesque rainforest, in fact—and a couple of medium-sized cities and an airport are within an hours’ drive. We later learned that the electricity in town was sporadic and that the hotel accommodations were expensive but shoddy. And along the downtown strip, half-constructed buildings seemed frozen in their incompleteness, as if they were as ambivalent about the future as the inhabitants were. Roofless, these cinderblock buildings stood mute and abandoned alongside the central beachfront road, rusting rebar jutting out of the tops of their gray walls. In front of them, stacks of bricks lay idly on the sidewalk. This quiet fishing and farming village of a few thousand would like to reinvent itself as a tourist destination. Government efforts to create fishing cooperatives and plants for processing and freezing fish expanded Mexico’s annual catch in the 1970s and 1980s, but today Mexico’s coasts are dominated by U.S., Canadian, and Japanese boats, which catch ten times what Mexican boats do. Small-scale fishermen in places like Barra de Cazones fetch low prices for their fish, and high fuel prices take a sizable chunk of their meager earnings. With fishermen struggling, little investment in infrastructure, high interest rates, and few jobs, this lonely town’s main business, like that of the nearby villages of Volador and Agua Dulce, is out-migration. Archimedes, a proud and boisterous local entrepreneur, was frying several freshly caught fish in a wide skillet and extolling their virtues in a theatrical baritone.
Getting Back to Work in the ’Burg
Authors: Broughton Chad
Published: November 2020

Tracy Warner Began to worry after she got a rejection letter from Pizza Hut a few weeks after graduating from Western. She hadn’t heard on some manager-level jobs at the Carl Sandburg Mall, but she expected at least some positive responses from the entry-level ones. “We wish you luck in finding a job worthy of your skills,” read the Pizza Hut letter. “What’s that?” Warner said, exasperated. “Either my skills suck, or I have too many skills. Which is it? ’Cause I’m kind of curious! It’s flattering to be overqualified but it doesn’t pay the bills.” Warner hadn’t expected a dream job to suddenly appear, but she had hoped for more than a quiet phone and a growing pile of rejection letters. She just needed something, anything, to get by. Several months into 2007, the newly minted and distinguished WIU graduate was still unemployed and uninsured. Although sworn off factory life, a desperate Warner applied to Farmland Foods. When Maytag shuttered in 2004, Farmland, a massive, loud, hog disassembly operation, became the largest employer in this part of western Illinois. With about 1,200 to 1,400 cutters and slicers and a $60 million payroll, the slaughterhouse employed a couple hundred more than BNSF, the largest employer in Galesburg. Like Mike Smith, Warner was just looking for a wage, any wage, with a “1” in front of it, and Farmland, on Monmouth’s northern edge, was close. It was so close, in fact, that on some days Warner could smell the tangy mix of rendered hog, hydrogen sulfide, methane, and whatever else made up that vile smell in her house, a mile to the south. Farmland was a last resort for former Maytag workers. The jobs there, involving tearing apart pig carcasses with razor-sharp knives and powerful pneumatic tools were, frankly, tougher than appliance work. Perhaps worst was the “sticker,” which slit the throats of about 1,000 shrieking animals each hour for about $12 an hour. That was one pig every four seconds, at about a penny per kill.
Genetic Algorithm (GA) and Internal Energy Transfer Calculations Using Neural Network (NN) Methods
Authors: Raff Lionel , Komanduri Ranga , Hagan Martin , Bukkapatnam Satish
Published: November 2020

Genetic algorithms (GA), like NNs, can be used to fit highly nonlinear functional forms, such as empirical interatomic potentials from a large ensemble of data. Briefly, a genetic algorithm uses a stochastic global search method that mimics the process of natural biological evolution. GAs operate on a population of potential solutions applying the principle of survival of the fittest to generate progressively better approximations to a solution. A new set of approximations is generated in each iteration (also known as generation) of a GA through the process of selecting individuals from the solution space according to their fitness levels, and breeding them together using operators borrowed from natural genetics. This process leads to the evolution of populations of individuals that have a higher probability of being “fitter,” i.e., better approximations of the specified potential values, than the individuals they were created from, just as in natural adaptation. The most time-consuming part in implementing a GA is often the evaluation of the objective or the fitness function. The objective function O[P] is expressed as sum squared error computed over a given large ensemble of data. Consequently, the time required for evaluating the objective function becomes an important factor. Since a GA is well suited for implementing on parallel computers, the time required for evaluating the objective function can be reduced significantly by parallel processing. A better approach would be to map out the objective function using several possible solutions concurrently or beforehand to improve computational efficiency of the GA prior to its execution, and using this information to implement the GA. This will obviate the need for cumbersome direct evaluation of the objective function. Neural networks may be best suited to map the functional relationship between the objective function and the various parameters of the specific functional form. This study presents an approach that combines the universal function approximation capability of multilayer neural networks to accelerate a GA for fitting atomic system potentials. The approach involves evaluating the objective function, which for the present application is the mean squared error (MSE) between the computed and model-estimated potential, and training a multilayer neural network with decision variables as input and the objective function as output.
The Oxygenates: Their Properties, Sources, and Use as Alternative Fuels
Authors: Calvert Jack , Mellouki Abdelwahid , Orlando John , Pilling Michael , Wallington Timothy
Published: November 2020

Partially oxidized organic compounds, i.e., those containing carbon, hydrogen, and oxygen atoms, and optionally other heteroatoms, are often referred to as “oxygenates” because they contain O-atoms as well as a C-atom skeleton. These enter the atmosphere as emissions from various industrial and transportation-related operations, evaporation and release from home usage of certain products, and release from vegetation. They are also formed in the atmosphere as oxidation products of all hydrocarbon emissions that enter the atmosphere from mobile and stationary sources as well as natural emissions from plants and animals. The common oxygenates consist of the alcohols (ROH), ethers (ROR), aldehydes (RCHO), ketones [RC(O)R], esters [RC(O)OR], and acids [RC(O)OH] together with N-atom-containing oxygenates and other less abundant classes of oxygen-containing organic compounds. The use of alternative fuels is increasing and is anticipated to continue to grow in the future. Many of these alternative fuels are oxygenates: methanol, ethanol, butanol, fatty acid methyl esters, and other biofuels. Thus, the scientific community is interested in identifying the important sources and sinks for these compounds. As with the hydrocarbons, the oxygenates serve as fuel for the reactions that generate ozone and other air pollutants within the troposphere. In illustration, consider the influence of the very common and important oxygenate, formaldehyde (CH2O).
Rate Coefficients and Mechanisms for the Atmospheric Oxidation of the Organic Acids
Authors: Calvert Jack , Mellouki Abdelwahid , Orlando John , Pilling Michael , Wallington Timothy
Published: November 2020

Organic acids, particularly formic and acetic acid, are ubiquitous components of the troposphere (Chebbi and Carlier, 1996); see table I-D-1. However, the atmospheric budget of these species is at present poorly constrained, and global models often underestimate their abundance (von Kuhlmann et al., 2003). The presence of organic acids in the atmosphere can be attributed to two distinct mechanisms: direct emission from anthropogenic and natural sources; and in situ production via gas-phase or condensed-phase chemistry. Direct emissions result from biomass burning (e.g., Christian et al., 2007), from motor vehicle use (Kawamura et al., 2000) and other anthropogenic activities (see chapter I), and from biogenic sources (e.g., Seco et al., 2007). Production in the gas phase can occur via the reactions of acylperoxy radicals with HO2: . . . CH3C(O)O2 + HO2 → CH3C(O)OOH + O2 . . . . . . CH3C(O)O2 + HO2 → CH3C(O)O + OH + O2 . . . . . . CH3C(O)O2 + HO2 → CH3C(O)OH + O3 . . . or via the ozonolysis of unsaturated species (Orzechowska and Paulson, 2005a, b). Additional in situ acid production (particularly with multi-functional species and diacids) likely occurs in the condensed phase as well, via the oxidation of carbonyl and other oxygen-containing and multi-functional organics (e.g., Ervens et al., 2004). In general, the organic acid moiety, —C(O)OH, is rather unreactive in the gas phase. This is in large part due to the strength of the O—H bond, ∼460 kJ mole−1 versus 400–420 kJ mole−1 for typical C—H bonds (Sander et al., 2006). The organic acid moiety also acts to inhibit somewhat the reactivity of neighboring sites (Kwok and Atkinson, 1995), further decreasing the reactivity of small saturated acids. UV spectra for unsubstituted acids are located at relatively short wavelengths, [e.g., λmax< 210 nm for acetic acid, Orlando and Tyndall (2003); see figure IX-A-1], so tropospheric photolysis is of negligible importance. Thus, the gas-phase lifetime for small saturated organic acids (e.g., formic and acetic acid) can be quite long, about 1 month.
Rate Coefficients and Mechanisms of Atmospheric Oxidation of the Esters
Authors: Calvert Jack , Mellouki Abdelwahid , Orlando John , Pilling Michael , Wallington Timothy
Published: November 2020

Esters are emitted directly into the atmosphere from both natural and anthropogenic sources and are produced during the atmospheric oxidation of ethers. Methyl acetate and ethyl acetate have found widespread use as solvents. Vegetable oils and animal fats are esters. Transesterification of vegetable oils and animal fats with methanol gives fatty acid methyl esters (FAMEs) which are used in biodiesel. Many esters have pleasant odors and are present in essential oils, fruits, and pheromones, and are often added to fragrances and consumer products to provide a pleasant odor. Table VII-A-1 provides a list of common esters and their odors. It is surprising to note that despite their ubiquitous nature, volatility, and fragrance, it is only very recently that quantitative measurements of esters in ambient air have been reported (Niedojadlo et al., 2007; Legreid et al., 2007). The atmospheric oxidation of saturated esters is largely initiated by OH radical attack. Reaction with O3 and NO3 radicals contributes to the atmospheric oxidation of unsaturated esters. As discussed in chapter IX, UV absorption by esters is only important for wavelengths below approximately 240 nm and, hence, photolysis is not a significant tropospheric loss mechanism. When compared to the ethers from which they can be derived, the esters are substantially less reactive towards OH radicals. The ester functionality —C(O)O— in R1C(O)OR2 deactivates the alkyl groups to which it is attached with the deactivation being most pronounced for the R1 group attached to the carbonyl group. The atmospheric oxidation mechanisms of the esters are reviewed in the present chapter. The reaction of OH with methyl formate has been studied by Wallington et al. (1988b) and Le Calvé et al. (1997a) over the temperature range 233–372 K. Data are summarized in table VII-B-1 and are plotted in figure VII-B-1. The room temperature determination of k(OH + CH3OCHO) by Wallington et al. is in agreement with that by Le Calvé et al. (1997) within the experimental uncertainties. Significant curvature is evident in the Arrhenius plot in figure VII-B-1.
Mechanisms of Photodecomposition of the Sunlight-Absorbing Oxygenates
Authors: Calvert Jack , Mellouki Abdelwahid , Orlando John , Pilling Michael , Wallington Timothy
Published: November 2020

In this chapter we consider the chemical changes induced by absorption of sunlight by oxygenated organic compounds. In contrast to the hydrocarbons, sunlight absorption by the oxygenated products of hydrocarbon oxidation shows a shift in absorption to the longer wavelengths such that their photodecompositions can become important atmospheric processes. This is illustrated in the absorption data given for methane and its oxidation products in figure IX-A-1. As a H3C—H bond in methane is replaced with a H3C—OH bond (alcohols), H3C—OCH3 bond (ethers), or H3C—O2H bond (hydroperoxides), light absorption involving excitation of nonbonding O-atom electrons to an antibonding sigma orbital (n → σ* transitions) becomes possible. These “forbidden” absorptions are smaller than the allowed σ → σ*transitions in the CH4 and the other alkanes, but the absorption bands are shifted to longer wavelengths progressing from CH4 to CH3OH, CH3OCH3, and CH3OOH as less energy is required to excite the nonbonding electron to the σ* orbital.
Working with Audio
Authors: Manzo V. J
Published: November 2020

In this chapter, we will discuss MSP, a collection of objects that work with audio signals. Unlike the Max objects we’ve discussed so far that handled data like numbers (including MIDI) and text, the MSP objects can handle actual sound recordings, like audio from a microphone, as well as generate signals. As we will see, MSP objects have a ~ after their name and slightly different colored patch cords signifying that they are handling some sort of audio signal. By the end of this chapter, you will be able to get a microphone signal in and out of Max, generate timbre according to the harmonic series, and build your very own synthesizer from that timbre. Let’s begin by building a basic patch that takes input from a microphone and sends it out to your speakers. Your computer is a digital device; you, as I hope you know, are not. Your voice is an acoustic instrument which, in the early days of recording, used to be recorded using analog recording techniques to represent qualities of the acoustic instrument. In order for your voice to be recorded and represented by a computer, there needs to be some conversion of the analog signal to a digital signal. For this reason, your computer’s sound card has an analog to digital converter, otherwise known as an A to D converter or, simply an ADC. Depending on the type of sound card you have, some AD converters will do a better job than others of supplying enough digits to represent the analog sound being recorded. Think about it like this: if you were allowed 50 words to describe your favorite food, the description would be a lot more articulate than if you had only 15 words to describe your favorite food. In the same regard, in a digital recording system, the more digits you have to represent the analog signal you are recording, the closer the representation will be to the original source you can hear with your ears. For now, we will leave this discussion of analog to digital conversion.
Janos: A Mirror in Time
Authors: deBuys William
Published: November 2020

The rains have forsaken El Cuervo for nearly a year, and the mountain-ringed plain that used to be a prairie is as naked as a parking lot. Not a blade of grass is in sight, scarcely a bush. A few low mesquites, defoliated and dormant, hug the parched ground, the wind having packed into their thorny embrace the dried-out stems of last year’s tumbleweeds. Except in the burrows of the kangaroo rats, nothing can be hidden here. A lost coin or key would shout its presence, much as the potsherds do on the mounds of the ancient pueblo by the arroyo. Every edible thing has been consumed, every plant nipped off at the level of the ground. Even the soil is leaving, blown away, tons to the acre, by winds that sweep down from the Sierra Madre, a dozen miles to the west. If you were to make your way to the top of one of the chipped-tooth peaks of the sierra (no small task), you would be able to look down into great canyons. One of those canyons belongs to the Río Gavilán, where in 1936 Aldo Leopold glimpsed a kind of ecological heaven that no longer exists. From atop the peak you would also see for great distances, certainly as far as Janos, the crossroads and market town through which nearly every visitor to this northwest corner of Chihuahua passes, and on a dustless day you might see the gritty penumbra of Ciudad Juárez and El Paso, far on the northeastern horizon. The air is dry, and here it is empty of pollution, which makes El Cuervo and its environs a good place for looking long distances, even into the past. One way to understand changes in the land is to visit a place that shows how things used to be. That’s what Leopold realized when he visited the Río Gavilán. He saw it as a fragment of the Southwest that had escaped the pressures of white settlement, and he recognized it as a mirror of how Arizona and New Mexico used to be, back in the days when the Apaches still roamed their homeland in freedom.
Lava Falls: The Blood of Oasis Civilization
Authors: deBuys William
Published: November 2020

Rightly or wrongly, everything challenging on a whitewater river in North America gets compared to the booming rapid that culminates, in space, time, and difficulty, a river trip through the Grand Canyon. Say “Lava” to anyone who has tasted whitewater, and the association to Lava Falls Rapid is automatic. A friend who guides trips on some of Alaska’s wildest rivers bristles when she hears the name Lava North applied to the most sphincter-tightening, life-or-death rapid on the mighty Alsek River. “It shows how Grand Canyon–centric the rafting world is,” she says. Advocates for other rivers say much the same. Still, Lava is king, and the Colorado River, for which Lava is a mere riffle in its eons of canyon carving, is the most mythic of river kingdoms. If you have a weakness for wild rivers, eventually you float the Colorado, and eventually you make your way to the Grand Canyon and to Lava. The drop at Lava Falls is thirteen feet almost immediately, followed by fourteen more in a few hundred yards. At most water levels, Lava earns a difficulty rating of ten, on a scale of ten. It confronts you at mile 179 on the 226-mile voyage from Lees Ferry to Diamond Creek, an incomparable outdoor adventure. The trip has the shape of a well-crafted novel. It establishes its themes in the red-rock stillness of Marble Canyon. It tests its characters in the churning whitewater of the Inner Gorge. Then Lava comes exactly where a novelist would place the climax, about four-fifths of the way through the saga. All the way down the river, you have had Lava in the back of your mind. Everything that precedes it feels like lead-up. Everything that follows is coda, resolution, release, perhaps recovery. The crux of the tale, the defining moment, resides in the hurricane waters of Lava Falls. By the time our small flotilla got there, we’d courted disaster at Crystal, dodged the rock horns of Horn Creek Rapid, ridden the roller coaster of Granite, and thrashed and crashed our way through scores of other rapids.