bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions at the carboxy group of an amino acid𠄔esterification of amino acids
Authors: Barrett Graham c. 
Published: November 2023

Abstract
The conversion of the carboxy group into derivatives by acid-catalysed nucleophilic addition, or into other functional groups by reductive processes, is neither always simple nor always quantitatively successful with free amino acids as starting materials. But esterification with simple alkanols is an uncomplicated procedure. This is because amino acids will slowly dissolve in hot alkanols, and these alkanols will also dissolve a strong acid catalyst, and also because the amino group is protonated under these conditions. Without protonation, the amino group would exert its nucleophilic property and compete with nucleophilic reactions at the carbonyl carbon atom.
Synthetic uses of serine, threonine and cysteine
Authors: Meffre Patrick , Vo-Quang Liliane , Vo-Quang Yen , Goffic Francois Le 
Published: November 2023

Abstract
L-serine, L-threonine and L-cysteine are useful optically active precursors for the asymmetric synthesis of a wide variety of molecules such as amino acids1-3 or other nitrogen-containing targets. Commercially available, they offer a great challenge to the synthetic chemist in terms of stereochemical control and efficiency. In particular, the preparation of various serine-, threonine- and cysteine-derived aldehydes for synthetic purposes requires four conditions: Carboxy group modifications are generally undertaken after suitable protection of the OH (or SH) and NH2 functionalities. The preparation of N protected a-amino aldehydes has received much attention in recent years.13 They are usually purified by vacuum distillation,
Metal-mediated modification of the side-chains of a-amino acids
Authors: Crisp Geoffrey T 
Published: November 2023

Abstract
a-Amino acids are fundamental building units in biology and chemistry. For chemists, the availability of proteinogenic a-amino acids provides ready access to a pool of chiral, non-racemic synthons for further elaboration. The current awareness of the relationship between the structure and the biological activity of peptides has generated interest in new methodologies which will enable the construction of unnatural amino acids and peptides which can probe enzyme specificity and modes of recognition.
Modifications of the aryl substituents of ß-aryl a-amino acids
Authors: Barrett Graham c. 
Published: November 2023

Abstract
Phenylalanine and tyrosine have the conventional chemistry of benzene and phenol, respectively when their amino and carboxy groups are protected. Similarly, histidine and tryptophan have the typical behaviour of a 4-substituted imidazole and a 3-substituted indole, respectively.
Isolation and chromatographic purification of reaction products from amino acids
Authors: Oȉneil Ian a. 
Published: November 2023

Abstract
Functionalized amino acids are highly versatile building blocks in organic chemistry. Their ready availability and low cost has meant that they are widely used in organic synthesis. Recrystallization is often used as a method for purification, however this is not always applicable. The highly polar nature of this family of compounds means that purification by conventional flash chromatography is often difficult. In this chapter the use of a more appropriate technique, reversed-phase dry flash chromatography on a preparative scale, is reviewed. The use of reversed-phase HPLC and ion exchange chromatography will not be covered.
Equipment: the matrix-isolation cold cell
Authors: Dunkin Ian R 
Published: November 2023

Abstract
This chapter describes the major equipment needed for a matrix-isolation unit capable of performing various types of experiments, and gives designs of basic systems and advice on construction and maintenance. Chapter 3 deals with ancillaries, such as preparative vacuum lines, photolysis sources and spectrometers. All the items in the list above are discussed, together with some related topics. Descriptions of additional items of minor or ancillary equipment will be found in other chapters at the points where they are most relevant. Although as much helpful detail as possible has been included, there are as many ways of putting together a system as there are laboratories. Readers should thus regard the advice given about equipment as a general guide to what is needed rather than a set of immutable instructions. It is hoped that the discussion which follows will stimulate those interested in setting up a matrix laboratory to find their own most appropriate solutions.
Matrix photochemistry and spectroscopy with plane-polarized light
Authors: Dunkin Ian R 
Published: November 2023

Abstract
This chapter describes matrix experiments with plane-polarized light, in which molecules can be spatially oriented. Although not a major part of matrix photochemistry, the experiments are easily carried out, and can provide useful information about the symmetries of electronic and vibrational transitions and about molecular conformations. The experiments depend on the fact that, except for very small molecules, trapped species in matrices are not only prevented from diffusing but also from rotating.
Perturbation Theory Of Intermolecular Forces At Short Range
Authors: Stone A J 
Published: November 2023

Abstract
The perturbation theory for well-separated molecules described in Chapter 4 (the ‘longrange approximation’ or ‘polarization approximation’) is very successful if the molecules are a long distance apart, but at short range it fails completely. Part of the reason for the failure of the theory as usually formulated is that the multipole expansion breaks down, but as we have seen, the multipole expansion is not fundamental to the theory, since it is possible to use a ‘non-expanded’ treatment. We shall see in Chapter 7 how to overcome the failure of the multipole expansion to converge without resorting to this device.
Interactions Involving Excited States
Authors: Stone A J 
Published: November 2023

Abstract
When one of a pair of identical molecules is in an excited state, a new type of interaction becomes possible. Since either molecule can be excited, with the other in the ground state, there are two states involved, and they can mix under the influence of the inter molecular perturbation, one combination being stabilized and the other raised in energy. This effect operates at long range; there is no need for the molecular wavefunctions to overlap.
Sources Of Experimental Data
Authors: Stone A J 
Published: November 2023

Abstract
For the most part, this account has concentrated on methods of calculating intermolecular interactions, either analytically or from ab initio computations. However the pur pose of such calculations is to make it possible to predict the behaviour of molecules, in small aggregates or in the bulk, and in principle a knowledge of intermolecular potentials should make it possible to predict the outcome of any experiment on molecules that does not involve actual chemical reaction. Comparison of theory with experiment in cases where the result is known allows us to validate the theory and, in some cases, to calibrate unknown parameters. In this chapter we outline the experimental techniques that are useful in the study of intermolecular potentials. This is not intended to be a de tailed account; a fuller treatment may be found in the books by Gray and Gubbins (1984) and by Maitland et al. (1981).
Synthesis of a Structure Related to Hydantocidin
Authors: Hanessian S , Sanreau J -Y , Chemla, P 
Published: November 2023

Abstract
Discussion Points Propose a mechanism for step c with a rationalisation of the stereochemical outcome. What is the role of TBAF in step i? Further Reading For recent examples of the use of fluoride ion as a base, see: T. Sato and J. Otera, J. Org. Chem.,1995, 60,2627; see also: T. Sato and J. Otera, Synlett,1995, 845.
The Asymmetric Synthesis of Bryostatin Fragments
Authors: Brabander J De , Vandewalle, M 
Published: November 2023

Abstract
Discussion Points What is the purpose of the magnesium bromide etherate in step d? Propose an explanation for the observed stereochemical outcome of step g. Explain the role of the Seyferth reagent in the formation of product 6. What is the mechanism of this step?
16. Stereoselective Total Synthesis of (+)-Artemisinin
Authors: Avery M A , Chong W K M , Jennings-White, C 
Published: November 2023

Abstract
Discussion Points Suggest a motive for oxidising compound 2 before the alkylation step d. Explain the stereoselectivity observed in step h? What other ester could have directly afforded compound 7 via a Claisen rearrangement? Suggest a mechanism for the formation of compound 8, obtained upon ozonolysis of vinylsilane 7.
The Synthesis of (±)-Prosopinine
Authors: Cook G R , Beholz L G , Stille, J R 
Published: November 2023

Abstract
Discussion Points Suggest a mechanism for the annulation of alkyne 2 into the a-lactam 3. What product could be expected from the direct Baeyer-Villiger oxidation of compound 5? Propose a structure for compound 10. Compound 11 was formed in an 85: 15 mixture with its trans-isomer. Explain the selectivity of the reaction.
Total Synthesis of the Enantiomer of Hennoxazole A
Authors: Wipf P , Lim, S 
Published: November 2023

Abstract
Discussion Points What is the mechanism of the Evans-Mislow rearrangement in step c? Suggest a mechanism for the formation of compound 5. Explain the stereoselectivity observed in the Luche reduction step j. Further Reading For a mechanistic explanation of the selectivity of the Sharpless epoxidation, see: E. J. Corey, J. Org. Chem.,1990, 55,1693; P. G. Potvin and S. Bianchet, J. Org. Chem.,1992, 57, 6629. For reviews on the Birch reduction, see: P. W. Rabideau, Tetrahedron,1989, 45,1579; J. M. Hook and L. N. Mander, Nat. Prod. Rep.,1986, 3,35. For a review on the use of tetrapropylammonium perruthenate in organic synthesis, see: S. V. Ley, J. Norman and S. P. Marsden, Synthesis,1994, 7, 639. For an analysis of the mechanism of the Evans-Mislow rearrangement, see: D. K. Jones-Hertzog and W. L. Jorgensen, J. Org. Chem., 1995, 60, 6682; D. K. Jones-Hertzog, W. L. Jorgensen, J. Am. Chem. Soc., 1995, 117,9077.
Total Synthesis of (+)-Duocarmycin A
Authors: Boger D L , McKie J A , Nishi T , Ogiku, T 
Published: November 2023

Abstract
Discussion Points Step k was carried out by adding the LDA to the substrate. It was found that if the substrate was added to the base, an almost complete inversion of the newly formed quaternary stereocentre ato the imine was obtained. Suggest an explanation for this observation. Further Reading For a review on the use of allylstannanes see: E. J. Thomas, Chemtracts, 1994, 7, 207.
Total Synthesis of (+)-Pyripyropene A
Authors: Nagamitsu T , Sunazuka T , Obata R , Tomoda H , Tanaka H , Harigaya Y , Omura S , III, A B Smith 
Published: November 2023

Abstract
Discussion Points Explain the stereoselectivity observed in steps a and p. Give reasons for the use of the Kuwajima methylation protocol of steps d and e. What purpose does sodium thiolate serve in step I? Explain the mechanism of step o. Further Reading For the biosynthesis of pyripyropene A, see: H. Tomoda, N. Tabata, Y. Nakata, H. Nishida, T. Kaneko, R. Obata, T. Sunazuka, and S. Omura, J. Org. Chem.,1996, 61,882. For a review on the use of enol triflates in olefin synthesis, see: W. J. Scott and J. E. McMurry, Acc. Chem. Res.,1988, 21,47. For the acylation reaction of 4-hydroxy-2-pyrone, see: E. Marcus, J. F. Stephen and J. K. Chan, J. Heterocycl. Chem.,1969, 6,13.
Total Synthesis of (-)-Papuamine
Authors: McDermott T S , Mortlock A A , Heathcock, C H 
Published: November 2023

Abstract
Discussion Points Suggest a synthesis of starting material 1. What is the purpose of ethanolamine in the work-up of step k? What is the mechanism of step n? No coupling reaction occurred when step q was performed in the absence of Cul. Suggest a possible reason for this finding. Further Reading For a related approach to the total synthesis of (+)-papuamine, see: A. G. M. Barrett, M. L. Boys and T. L. Boehm, J. Org. Chem.,1996, 61, 685. For a review on the palladium-catalysed reaction of organotin compounds, see: T. N. Mitchell, Synthesis,1992, 9,803.
Total Synthesis of (+)-Dolabellatrienone
Authors: Corey E J , Kania, R S 
Published: November 2023

Abstract
Discussion Points Suggest a synthesis of chloride 1 from (E,E)-farnesol? What is the mechanism of step i? Rationalise the stereochemical outcome in terms of the stereochemistry of the starting material 6 and the intermediates formed during the transformation. What symmetry does catalyst 7 possess? What reagents would usually be employed to effect the transformation of olefin 9 into 10 ?
Total Synthesis of (+)-FR900482
Authors: Yoshino T , Nagata Y , Itoh E , Hashimoto M , Katoh T , Terashima, S 
Published: November 2023

Abstract
Discussion Points Apart from the high temperatures used in this synthesis, suggest alternative conditions which can be used to promote the transformation canied out in step c. What is the mechanism of step k? What are the standard conditions for the removal of a Boe protecting group from an amine? Are these conditions compatible with the deprotection of compound 10? Propose a structure for compound 12.
Total Synthesis of (+)-Acerosolide
Authors: Paquette L A , Astles, P C 
Published: November 2023

Abstract
Discussion Points Treatment of aldehydes with allylstannane 1 in the presence of BF3 would normally afford branched homoallylic alcohols. Suggest a mechanism for the regiochemical outcome of the reaction run in step a What relative stereochemistry is to be expected from the Nozaki reaction of step I? Further Reading For a review on the Nozaki reaction, see: P. Cintas, Synthesis,1992, 248.
The Synthesis of Picrotoxinin
Authors: Trost B M , Krische, M J 
Published: November 2023

Abstract
Discussion Points Propose a motive for the stereoselectivity of step c. Give a mechanism for step h. Bearing in mind the stereochemistry of epoxide 11, propose a mechanism for its acid-catalysed ring opening under the conditions of step o. Suggest a possible reason for the increased stability of five-membered ring lactone 14 compared to the six-membered ring bridged system 13.
Total Synthesis of (+)-Dactylol
Authors: Molander G , Eastwood, P R 
Published: November 2023

Abstract
Discussion Points Propose a mechanism for the [3 + 5] annulation step b. What is the mechanism of the Tebbe methylenation reaction? The desired product 6 was isolated in only 25% yield. Bearing in mind the mechanism of the dissolving metal ring opening reaction, suggest a structure for the major product (36%) isolated from the reaction mixture.
Synthesis of Staurosporine Aglycon
Authors: Moody C J , Rahimtoola K F , Porter B , Ross, B C 
Published: November 2023

Abstract
Discussion Points What is the mechanism of step b? Propose a mechanism for the transformation covered in step f. Simply refluxing compound 7 under an inert atmosphere in bromobenzene gave a product 10 in high yield. In the proton NMR spectrum of this product there were the following signals integrating for single protons; o 3.28 (dd, J= 17 and 7 Hz), o 3.69 (dd, J= 17 and 10 Hz), o 4.72 (dd, J= 10 and 7 Hz). The FAB·mass spectrum gave a protonated molecular ion at 346 mle.Suggest a structure for this compound and the motive for a second reflux of the reaction mixture in air.
A Total Synthesis of Taxol
Authors: Masters J J , Link J T , Snyder L B , Young, W B , Danishefsky, S J 
Published: November 2023

Abstract
Discussion Points What is the mechanism of step a? What is the purpose of aluminium triisopropoxide in step b? Give reasons for the selectivity (4:1) obtained in the osmylation step c. When fluoride ion was used instead of ethylene glycol as the desilylating agent to promote the formation of the oxetane ring in 3, the main product isolated was 12. Suggest the mechanism for its formation. Explain the diastereoselectivity observed in the formation of compound 8. Explain the stereo selectivity of epoxidation step t. Give reasons for the regioselectivity observed in the epoxide reduction step u. Suggest a way of synthesising 7.
Biological olfaction
Authors: Gardner Julian W , Bartlett Philip N 
Published: November 2023

Abstract
Our knowledge of the mammalian olfactory system is as yet incomplete, although spectacular progress has been made in the last few years by applying techniques from molecular biology to the problem. In this chapter we present an overview of our current knowledge of the organisation and functioning of the mammalian olfactory system at the molecular level. We also discuss the psychophysical aspects of olfaction which describe the human sensitivity and response to flavour and odour.
Electronic nose instrumentation
Authors: Gardner Julian W , Bartlett Philip N 
Published: November 2023

Abstract
The basic elements of a generalised electronic instrument system to measure odours are shown schematically in Fig. 8.1. First there is an odour delivery system which is designed to transfer the odour from the source material to the sensor chamber. There are two main ways in which the odour can be delivered to the sensor chamber, namely headspace sampling and flow injection. In headspace sampling, the head-space of an odorant material is physically removed from a sample vessel and inserted into the sensor chamber using either a manual or automated procedure (Section 8.2.1). Alternatively, a carrier gas can be used to carry the odorant from the sample vessel into the sensor chamber by a method called flow injection (Section 8.2.2). The sensor chamber houses the array of chosen odour sensors, e.g. semiconducting oxide, conducting polymer chemoresistors, etc. The sensor electronics not only convert the chemical signal into an electrical signal but also, usually, amplify and condition it. This can be done using conventional analogue electronic circuitry (e.g. operational amplifiers) and the output is then a set of n analogue outputs, such as Oto 5 V d.c., although a 4 to 20 mA d.c. current output is preferable if using a long cable. The signal must be converted into a digital format to be processed by a computer, and this is carried out by an analogue to digital converter (e.g. a 12-bit converter) followed by a multiplexer to produce a digital signal which either interfaces to a serial port on the microprocessor (e.g. RS-232) or a digital bus (e.g. GPIB). The microprocessor (e.g. an Intel 486 or Motorola 68HC11) is programmed to carry out a number of tasks.
Applications and case studies
Authors: Gardner Julian W , Bartlett Philip N 
Published: November 2023

Abstract
Electronic nose instrumentation has been used to measure both simple and complex odours in many fields of application to date. The nature of the application itself is important and there are a large number of critical factors which are important to consider. For the sake of convenience, these factors have been grouped under three distinct headings, namely the nature of the test, the measurement conditions, and. the nature of the measurand.
The nature of the test can vary considerably. For example, Table 9.1 lists a number of different kinds of tests that can be undertaken with an electronic nose.
Introduction
Authors: Ravindranath N H , Hall D O 
Published: November 2023

Abstract
Developing countries firmly believe that economic growth and development are necessary to reduce poverty and human deprivation. Such growth and development also offer a way of limiting unsustainable population increases; any constraints on growth could be counterproductive (WEC 1993). Thus developing countries are keen on achieving higher growth and exports. Inherent in their plans for economic expansion is the positive relationship between energy and GDP (gross domestic product). For example, the commercial energy growth rate in India during the 1980s was around 4.5 per cent (electricity at 9.2 per cent) per annum, comparable with a GDP growth rate of about 5 per cent (PC 1992). Similarly, in low-income countries generally, commercial energy consumption is growing at 3.6 per cent annually compared to a GDP growth rate of 2.5 per cent (WB 1992). What is disturbing is that the oil and electricity intensities of GDP for a country such as India are increasing even after past experiences of oil supply and price crises (TERI 1992a; OECD 1993).
Environmental impacts of biomass energy
Authors: Ravindranath N H , Hall D O 
Published: November 2023

Abstract
The extraction, conversion, and utilization of various forms of energy is recognized as one of the major contributors to environmental degradation at the global as well as the local level; be it greenhouse gas emissions and local air pollution due to combustion of fossil fuels, submergence of forests by hydroelectric power projects, or forest degradation due to fuel wood use.
Assessment of bioenergy programmes in India
Authors: Ravindranath N H , Hall D O 
Published: November 2023

Abstract
The dominance of biomass energy in the energy consumption pattern of India has been highlighted in earlier chapters. The population in India is growing at a rate of about 2.12 per cent annually and it is observed that biomass use is keeping pace with population growth. The use of biomass as a traditional fuel is associated with a lower quality of life and environmental degradation. It is thus necessary to understand what India is doing to alleviate such problems associated with the dependence on and use of biomass and to draw lessons therefrom before exploring the potential role for bioenergy in promoting sustainable development.
Land and biomass availability for sustainable bioenergy
Authors: Ravindranath N H , Hall D O 
Published: November 2023

Abstract
In previous chapters the potential and the technical and operational feasibility of biomass electricity systems for both decentralized village-level and megawatt level systems were shown. The utilization of this large bioenergy potential requires sustainable supplies of biomass, particularly woody biomass. Thus the woody biomass requirement, the current biomass availability, and options for sustainable supply have to be considered. In a developing country such as India the crucial question always asked is whether it would be able to simultaneously meet the food requirements of a growing population and supply biomass for energy sustainably. Food production is always a priority, and thus it is necessary to analyse the food-fuel issue and the current woody biomass production programmes with reference to India.
Implications for bioenergy in developing countries
Authors: Ravindranath N H , Hall D O 
Published: November 2023

Abstract
In our analysis we have shown the need and the potential for bioenergy, and the possible economic, social, and environmental benefits for India. If bioenergy options are feasible for India, a country with a high population density and poor biomass resources (low forest and pasture area per capita), it should, at least theoretically, be even more feasible for many developing countries in sub-Saharan (SS) Africa, South-East Asia, and South America, with lower population densities and larger biomass resources (Table 1.2). Although it is tempting to undertake such an analysis at the macro level for other countries, one must be acutely aware of the limitations of such an exercise, especially if there is insufficient knowledge of the individual country. However, based on our analysis for India, some broad issues on rural energy, particularly the technical potential of bioenergy in some selected developing countries, are considered. No attempt is made to make any specific recommendation for any one country.