bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure generation
Authors: Besson J M 
Published: November 2023

Abstract
The instruments and methods which have been used for the generation of high pressures are probably more diverse than those in any other field of instrumentation. Since the high-pressure field has long been considered as a closed domain, devoted to the study of matter under extreme or exotic conditions, it has frequently progressed under the impulse of highly dedicated individuals, or schools of thought, who drove to its ultimate limits one given technology or one given concept and more or less ignored alternative solutions. Thus, high-pressure technology seems to have evolved in the present century in a completely irrational way, in sharp contrast to low-temperature technology, which, since Kamerlingh Onnes at least, has followed a logical pattern of improvement. A few examples will illustrate this. About half a century ago, P. W. Bridgman devised and operated an intricate two-stage system to compress large volumes of gas (fluid) to 10 GPa. At the present time, no laboratory could repeat this feat. By contrast, the diamond-anvil cell (DAC), which is now the dominant device for high-pressure studies, was perfected in its complete form, that is, as a gasketed device, with a rubyfluorescence scale only in the 1970s, following work by S. Block and G. J. Piermarini. Nevertheless, all the necessary know-how and materials existed a century ago, and it is strange that no one thought of it before.
Introduction: techniques, transformations, correlations, and conformation
Authors: Jones D W 
Published: November 2023

Abstract
Given an amenable, preferably centrosymmetric, single crystal of an organic compound, then the determination of an individual crystal structure by X-ray diffraction well enough to establish connectivity can often be a near routine business. Of course, as mentioned in the final chapter, there are still many crystal structures that are, if not intractable, then extremely difficult to solve satisfactorily. In recent decades the interest of many crystallographers has focussed more on the structural correlations and interactions revealed by measurements on the structures of a series of compounds, both specifically determined and extracted from the database. There remain very many cases, for example powdery materials, or those with low melting point or with multiple or amorphous phases, for which a satisfactory crystal is not available and for which, therefore, a straightforward X-ray single-crystal analysis is not feasible at room temperature. In Part I are presented two kinds of experimental approach to structure determination applicable in some of these cases, together with a reminder that diffraction measurements yield data about the motions as well as the positions of atoms.
Crystal chemical design of prototropic systems with intra-and inter-molecular transfer of protons: results and prospects for practical application
Authors: Aldoshin S M , Chuev I I 
Published: November 2023

Abstract
In recent years the study of crystal chemical aspects of solid phase transformations was one of the main topics of investigation for the Institute of Chemical Physics (Chernogolovka). Investigations of such reactions are preferred to those in the liquid phase because: a) the initial state of the system can be determined by X-rays; b) in suitable cases the crystal structure of the solid matrix stabilizes intermediates which can be studied by X-ray or spectroscopic methods; c) if a reaction does not occur on the macro-or micro-defects, correlation between the character of the reaction and the crystal structure of the reagents can be deduced. In this case, topochemical principles of control for solid phase reactions can be formulated and this opens vast possibilities for “engineering of crystal structure” which is favourable for such reactions.
Long-range consequences of hydrogen bonding: a partial correlation approach to relationships among structural parameters
Authors: Wozniak K , Krygowski T M 
Published: November 2023

Abstract
Computer-assisted searches of the literature databases indicate that a paper on hydrogen (H)bonding is published every half hour (1). In most cases (1,2] these papers deal with the H-bonding itself - its geometry and energy of interactions - or with changes in physicochemical or biochemical properties.
Spherands, hemispherands and calixspherands
Authors: Verboom Willem , Reinhoudt David N 
Published: November 2023

Abstract
In 1979 Cram reported the synthesis of a novel class of macrocyclic host molecules composed of anisyl units that have rigid preorganized cavities. These so-called spherands, the prototype of which is 1, form very stable complexes with small alkaline cations (Li+, Na+). The high thermodynamic stabilities (Ka &gt; 1013 L mol−1) are due to the rigidity of the molecular framework which creates a high electron density directed in the cavity, generated by the oxygen lone pairs of anisyl moieties. Upon cbmplexation, the electronelectron repulsion of neighbouring oxygen lone pairs is relieved. This is a fundamentally different concept when compared with the complexation of cations by more flexible macrocyclic ligands, which require reorganization of the ligand prior to or during complexation, although in the complexation of cations by crown ethers, relief of oxygen-oxygen repulsions may also contribute. The concept of preorganization has been further extended by Cram and his group, for example by variation of the ring size and by substitution of one or more anisyl units by methoxycyclohexyl, urea or phenanthroline subunits.
Synthons derived from aspartic and glutamic acids
Authors: Moloney Mark G 
Published: November 2023

Abstract
Glutamic and aspartic acids are both proteinogenic amino acids widely distributed in nature. They are amongst the cheapest commercially available amino acids, obtainable as either enantiomer in homochiral form, and because of their side-chain functionality, make useful starting materials for stereoselective organic synthesis.11-5 However, because of the presence of three functional groups in these amino acids, and because of the potentially epimerizable a centre, suitable protection is generally required in order to obtain a synthetically useful intermediate, and this is particularly true for reactions involving deprotonations. Protection must be achieved in a manner which also enables convenient and efficient deprotection, to enable the manipulation of the functionalized intermediates into amino acid and other products.
Synthetic uses of methionine
Authors: Meffre Patrick , Vo-Quang Liliane , Vo-Quang Yen , Goffic Francois Le 
Published: November 2023

Abstract
The synthetic utility of amino acids for the generation of chiral reagents, intermediates and final products is now well documented. Naturally occurring L-methionine is an interesting source of chiral starting material. After appropriate amino and carboxy-protection, side-chain modifications provide chiral protected vinylglycine 11 and aspartic acid j3-semialdehyde 2, two attractive a-amino acid chiral building blocks.
Diastereocontrolled functionalization of enantiomerically pure 5-phenyl-11,4-oxazin-2-ones by azomethine ylid generation and trapping
Authors: Harwood L M , Lilley i. A , Cox g. G , Williams c. E 
Published: November 2023

Abstract
The conformational rigidity of the 1,4-oxazin-2-one ring makes it an ideal template for diastereocontrolled reactions and several groups have profited from this property in the area of asymmetric synthesis of enantiomerically pure a-amino acids.
Reactions at the a-carbon atom of a-amino acid derivatives
Authors: Barrett Graham c. 
Published: November 2023

Abstract
For the common a-amino acids, racemization is the classic example of a reaction under this heading. a,a-Disubstituted glycines H3N+-CR11R2-Co2-, prepared through C-alkylation of a glycine synthon (another classic example of a reaction at the a carbon atom), are stable towards racemization because they lack an a proton. Removal of the a proton and a leaving group at the (3 position (simple a,(3-elimination leading to a-aminoacrylates R11NH-C( =CHR2)-CO2R3; alias 𠄘dehydro-amino acids𠄙) represents the remaining major category of reaction
The Theory of Intermolecular Forces
Authors: Stone A J 
Published: November 2023

Abstract
There have been many developments in the theory of intermolecular forces over the last twenty years or so that have not so far been collected together in book form. After many years of effort, practical methods have emerged for the accurate calculation of intermolecular interactions by perturbation theory. Increasing computer power is making it possible to pension off the Lennard-Jones potential after 75 years of valuable service and to use more realistic models; similarly point-charge models are giving way to more so phisticated multipole descriptions. This has come at a time when experimental methods for determining intermolecular potentials are becoming more and more powerful and re liable, and when interest in accurate models of intermolecular interactions is greater than ever before, not least because of the increasing use of computer modelling for simulating systems of biological interest and for designing biologically active molecules for use as drugs and pesticides and the like.
Circular Dichroism and Linear Dichroism
Authors: Rodger Alison , Norden Bengt 
Published: November 2023

Abstract
This book provides an introduction to all those who wish to use the complementary spectroscopic techniques of optical activity (circular dichroism, CD) and optical anisotropy (linear dichroism, LD) for the study of the structure of molecules and interactions between molecules in solution. It emphasizes these techniques and how to use them for both low and high molecular weight molecules. The book begins by describing the principles behind CD and LD and how these techniques can be used in the laboratory without using advanced maths or quantum mechanics. The next chapters describe how both techniques may be applied to the study of biological macromolecules and give a detailed description of how they may be used on small molecules to investigate molecular and electronic structure. The final part contains theoretical derivations of all the equations required for the applications described previously. Specific molecular examples are used to illustrate concepts and to show the reader how to use the techniques in chemical and biological systems. Circular Dichroism and Linear Dichroism is an easy guide to what a prospective user of CD needs to know and explains how LD is not merely an exotic technique only to be practiced by experienced spectroscopists, but may be routinely and usefully employed as an aid to molecular structure determination.
Circular dichroism of biomolecules
Authors: Rodger Alison , Norden Bengt 
Published: November 2023

Abstract
It is probably true that CD is now more widely used to study biological systems than non-biological systems. This is despite the fact that the molecules concerned are usually very large and therefore detailed structural analysis of their CD data is not yet possible. In this chapter we shall focus on the CD of proteins, nucleic acids, and nucleic acid-ligand systems. What is written here is by no means the last word on these subjects as the increasing interest in structural details of biological molecules means that all techniques that can be used to study these systems are the focus of active research.
Linear dichroism of biomolecules
Authors: Rodger Alison , Norden Bengt 
Published: November 2023

Abstract
In this chapter we shall see how LD can be used to study macromolecules of biological interest. In contrast to the previous chapter, we shall deal with proteins fairly quickly as LD has been less widely used for these molecules than for DNAs. Our main concern will be with DNA since LD, particularly flow and electric field LD, has been used to great effect in the study of the conformation of DNA and binding geometries of DNA-drug systems. Since LD is conceptually quite simple (much simpler than CD) the reader will be able to follow easily the deduction of structural information for biopolymers in the examples of this chapter. The formal mathematical framework for LD is presented in Chapter 4 for more general cases of LD spectroscopic applications.
Total Synthesis of (—)-Ovatolide
Authors: Delgado A , Clardy, J 
Published: November 2023

Abstract
Discussion Points What other isomer is formed in the nitration step a? Rationalise the regioselectivity of the mono-debenzylation reaction carried out in step b. Suggest a structure for compound 6 and give reasons for carrying out the reaction in a reductive environment. What is the mechanism of the hydrolysis of compound 8? Give an explanation for the use of ethylenediamine in step I. Further Reading For a review on diastereoselective nitroaldol reaction, see: D. Seebach, A. K. Beck, T. Mukhopadhyay and E. Thomas, Helv. Chim. Acta,1982, 65,1101. For a modification of the nitroaldol reaction using alumina, see: G. Rosini, E. Marotta, P. Righi and J. P. Seerden, J. Org. Chem.,1991, 56,6258.
Total Synthesis of RS-15385
Authors: Rohloff J C , Dyson N H , Gardner J O , Alfredson T V , Sparacino M L , III, J Robinson 
Published: November 2023

Abstract
Discussion Points What is the mechanism of the Bischler–Napieralski reaction of step b? Suggest a reason why less hindered bases could not be used in step f. Propose structures for the minor diastereomers obtained during the hydrogenation step g. Suggest a derivatising agent for the HPLC analysis of the optical purity of the 10-camphorsulphonic acid salt obtained in step h. Further Reading For reviews on isoquinoline alkaloids synthesis, see: M. D. Rozwadowska, Heterocycles,1994, 39,903; E. D. Cox and J.M. Cook, Chem. Rev.,1995, 95,1797. For a review on chiral derivatising agents, see: Y. Zhou, P. Luan, L. Liu and Z.-P. Sun, J. Chromatogr. B: Biomed. Appl.,1994, 659,109.
Asymmetric Synthesis of 1-Deoxy-8,8a-di-epi­ castanospermine
Authors: Martin S F , Chen H -J , Lynch, V M 
Published: November 2023

Abstract
Discussion Points Explain the stereoselectivity obtained in step a. Propose a mechanism for the conversion of 2 into 3. Suggest a structure for the intermediate formed in step j. Further Reading For oxidative opening of furans, see: B. M. Adger, C. Barrett, J. Brennan, M.A. McKervey and R. W. Murray, J. Chem. Soc., Chem. Commun.,1991, 21,1553. For an analysis of chelation-controlled carbonyl addition reactions, see: M. T. Reetz, Acc. Chem. Res.,1993, 26,462.
Total Synthesis of (-)-Swainsonine
Authors: Naruse M , Aoyagi S , Kibayashi, C 
Published: November 2023

Abstract
Discussion Points Explain the selectivity of the hetero Diels–Alder reaction of step I and suggest a reason for the lower selectivity (endo:exo 1.3:1) observed when the reaction was run in chloroform. Explain the selectivity observed in the osmylation step o. Further Reading For reviews on the use of the hetero Diels-Alder reaction in natural product synthesis, see: J. Streith and A. Defoin, Synthesis,1994, 11,1107; S. F. Martin, J. Heterocycl. Chem.,1994, 31, 619;H. Waldmann, Synthesis,1994, 6,535.
The Synthesis of (±)-Oxerine
Authors: Aoyagi Y , Inariyama T , Arai Y , Tsuchida S , Matuda Y , Kobayashi H , Ohta A , Kurihara T , Fujihira, S 
Published: November 2023

Abstract
Discussion Points What is the predominant reason for the selectivity of the allcylation step a? Propose a mechanism for step d. Propose a mechanism for the samarium iodide promoted cyclisation of acetylene 6. What is the reactive intermediate responsible for this step? Give reasons why the formation of cyclohexene 11 should be disfavoured. Why was it not possible to obtain alcohol 9 directly by hydroboration of olefin 7? What effect is responsible for the high diastereoselectivity observed in the methylation of ketone 8? Further Reading For a review on Baldwin’s rules, see: C. D. Johnson, Acc. Chem. Res., 1993, 26,476. For a recent review on samarium iodide, see: G. A. Molander and C.R. Harris, Chem. Rev.,1996, 96,307.
Studies Towards the Total Synthesis of Rapamycin
Authors: Anderson J C , Ley S V , Marsden, S P 
Published: November 2023

Abstract
Discussion Points What is the maximum theoretical yield for step a? Give a mechanism for the cyclisation step f? What is the use of PPh3 in step i? Explain the selectivity observed in step j. The anomer of 5 was found to react with lower selectivity. Suggest a reason for this finding. Propose a synthesis of vinyl iodide 8. How could the minor, undesired diastereomer obtained in the Nozaki-Kishi condensation of step n be converted into 9? Further Reading For the use of enzymes in organic solvents, see: A. L. Gutman and M. Shapira, Adv. Biochem. Eng./Biotechnol.,1995, 52,87; L. Kvittingen, Tetrahedron,1994, 50,8253; A. P. G. Kieboom, Biocatalysis,1990, 357; C.H. Wong, Science,1989, 244,1145; C. S. Chen and C. J. Sib, Angew. Chem.,1989, 101,711; A. M. Klibanov, Trends Biochem. Sci.,1989, 14,141. For a review on the preparation and reactivity of alkenyl-zinc, -copper, and -chromium organometallics, see: P. Knochel and C. J. Rao, Tetrahedron, 1993, 49,29. For a review on the Nozaki-Kishi reaction, see: P. Cintas, Synthesis, 1992, 248. For the other papers in the series, see: C. Kouklovsky, S. V. Ley and S. P. Marsden, Tetrahedron Lett.,1994, 13,2091; S. V. Ley, J. Norman and C. Pinel, Tetrahedron Lett.,1994, 35,2095.
Studies Towards the Total Synthesis of Rapamycin
Authors: Kouklovsky C , Ley S V , Marsden, S P 
Published: November 2023

Abstract
Discussion Points How would it be possible to recycle the undesired synisomer obtained in step a? What is the mechanism of step c? Explain the diastereoselectivity observed in the (EJ-crotylborane addition to aldehyde 4. Rationalise the diastereoselectivity observed in the epoxidation of homoallylic alcohol 5. How could the stereoselectivity of this reaction be reversed? Further Reading For an analysis of the mechanism in the oxazaborolidine catalysed reduction of ketones, see: B. Ganem, Chemtracts: Org. Chem.,1988, 1,40. For a review on enantioselective reduction of ketones, see: V. K. Singh, Synthesis,1992, 7, 607. For a review on the diastereoselectivity in nucleophilic additions to unsymmetrically substituted carbonyls, see: B. W. Gung, Tetrahedron,1996, 52,5263. For reviews on the synthesis of chiral epoxides, see: P. Besse and H. Veschambre, Tetrahedron,1994, 50,8885; W. Adam and M. J. Richter, Acc. Chem. Res.,1994, 27, 57; K. A. J rgensen, Chem. Rev.,1989, 89,431. For a review on substrate-directable reactions, see: A.H. Hoveyda, D. A. Evans and G. C. Fu, Chem. Rev.,1993, 93,1307. For a review on epoxide chemistry, see: J. Gorzynski Smith, Synthesis, 1984, 629. For a review on intramolecular reactions of allylic and propargylic silanes, see: D. Schinzer, Synthesis,1988, 4,263. For a review on the use of chiral boranes in synthesis, see: D.S. Matteson, Chem. Rev.,1986, 973.
Stereoselective Synthesis of (+)-Aromaticin
Authors: Majetich G , Song J -S , Leigh A J , Condon, S M 
Published: November 2023

Abstract
Discussion Points What is the mechanism of step d? Give reasons for the use of two equivalents of Lewis acid in step e. During the ene reaction of step f, a regioisomer of 6 could, in theory, be formed. Propose a structure for this isomer and suggest a reason why its formation was not observed. Explain the stereoselectivity in steps h andj. Suggest a possible reason why the phenylselenation reaction of step o required acid catalysis. Further Reading For a review on the use of silanes in the synthesis of natural products, see: E. Langkopf and D. Schinzer, Chem. Rev.,1995, 95,1375.
Synthesis of 3α-Acetoxydrimenin
Authors: Swarts H J , Verstegen-Haaksma A A , Jansen B J M , Groot, A de 
Published: November 2023

Abstract
Discussion Points What governs the stereoselectivity of the 1,4-addition step a? Suggest a mechanism for the rearrangement in step e? Propose a mechanism for the non-basic formylation step j? Suggest a structure for a side-product of step n caused by the basicity of theDMAP. Further Reading For the application of Criegee’s rearrangement in the synthesis of enol ethers see: R. M. Goodman and Y. Kishi, J. Org. Chem.,1994, 59,5125.
Formal Synthesis of (±)-Aphidicolin
Authors: Toyota M , Nishikawa Y , Fukumoto, K 
Published: November 2023

Abstract
Discussion Points The condensation step a gave a 3 : 1 mixture of isomers 2. Assuming that the stereoselectivity of the reaction can be rationalised by a Zimmerman-Traxler transition state model, what should be the structure of the predominant isomer? What is the mechanism of step b? The tetracyclic product 9 was obtained in a 3 : 1 mixture with its epimer at C5. What is the mechanism of this reaction? Rationalise the stereochemical outcome. Further Reading For a recent review of the Heck reaction see: W. Cabri and I. Candiani, Acc. Chem. Res.,1995, 28,2.
Synthetic Efforts Towards Bruceantin
Authors: Chiu C K -F , Govindan S V , Fuchs P L 
Published: November 2023

Abstract
Discussion Points What is the controlling factor in the stereochemical outcome of the conjugate addition of cyanide to enone 1? Based on the above fact, what would you predict the product of step c to be? Give a rationalisation for the difference in reactivity displayed by epimers 7 and 8 under basic conditions. In the transformation of ketone 11 into nitrile 12 the phenylselenyl group undergoes epimerisation. What is the driving force behind this process? Suggest a mechanism for the oxidation step u carried out in the absence of triethylamine.
Synthetic Studies on Furanoheliangolides
Authors: Brown D S , Paquette, L A 
Published: November 2023

Abstract
Discussion Points Suggest a mechanism for the formation of furan 2. Rationalise the stereochemical outcome of step f. The transformation 3 -&gt; 6 involves the formal [4+2] cycloaddition of a ketene to the furan ring. Why are ketenes not usually employed directly for Diels-Alder reactions? Propose a suitable mechanism for the rearrangement of compound 14 to give the isomers 15 and 16. What role does the potassium carbonate play in the reaction? What product could be expected to be formed from the E-enol ether 17 under the conditions outlined in step r?
Total Synthesis of Staurosporine
Authors: Link J T , Raghavan S , Danishefsky, S J 
Published: November 2023

Abstract
Discussion Points What is the structure of the intermediate formed in step d? Suggest a reason for the closure of the oxazoline ring on the 8-face (formation of 4) and not on the a-face. Step j yielded a 2.5:1 mixture of a.:8 epoxides. Give reasons for the low stereoselectivity observed. The minor epoxide was found to react less efficiently with 2. Suggest a possible reason for this observation. The Boe protecting group on the oxazolidinone nitrogen of 10 plays a crucial role in steps x and y. Suggest the reason why it was introduced. What is the mechanism of step c’?
Instrumental and sensory analysis
Authors: Gardner Julian W , Bartlett Philip N 
Published: November 2023

Abstract
In this chapter we provide a brief introduction to the different techniques currently used in the evaluation of the odour and/or flavour of commercial products—including foodstuffs, beverages, perfumes, and other products. These techniques can be divided into instrumental analytical techniques and those using sensory evaluation by panels of human testers. These types of approaches are routinely used for a variety of purposes such as the development and evaluation of new products, quality control in the production of commercial products, and for evaluation and detection of taints and off-flavours. Our purpose in this chapter is to provide the reader with a general background against which the possible applications of electronic noses in these different areas can be viewed.