Ideal starting materials

Ideal starting materials for the preparation of. svn-aldols are ketones that can be readily deprotonated to give (Z)-enolates which are known to give predominantly yyu-adducts. Thus, when (5,)-1-(4-methylphenyl)sulfonyl-2-(l-oxopropyl)pyrrolidine is treated with dibutylboryl triflate in the presence of diisopropylethylamine, predominant generation of the corresponding (Z)-boron enolate occurs. The addition of this unpurified enolate to 2-methylpropanal displays not only simple diastereoselectivity, as indicated by a synjanti ratio of 91 9, but also high induced stereoselectivity, since the ratio of syn- a/.vyn-lb is >97 3. 

With the enhanced stability as compared to that of 63 e, 76 should be an ideal starting material for the construction of larger organometallic molecular objects of dendrimeric, cyclic or polymeric nature. 

The iminophosphorane 177 available from methyl azido(phenylhydrazo-no)acetate by a Staudinger reaction represents an ideal starting material for the synthesis of l//-l,2,4-triazoles (180). Two synthetic routes are possible (Scheme 68). The first is the reaction of iminophosphoranes with halides via isolable A-acylphosphonium salts (178), and imidoyl chlorides (179), leading to triazoles. The other approach involves the less reactive anhy-... 

Methanol is an ideal starting material for the synthesis of many chemicals. It is the most important feedstock for the large-scale commercial production of acetic acid and formaldehyde. Additionally, a variety of other chemicals such as methyl esters, methyl halides and methyl ethers can be produced from it. Tenessee-Eastman s recent pioneering commercialization of a coal-based process for acetic anhydride production illustrates the growing importance of methanol as chemical feedstock. 

Various metal alkoxides are ideal starting materials for the preparation of metal (hydrous) oxides by the described aerosol techniques, because many of these compounds are in the liquid state at room temperature, easily vaporized, and exceedingly reactive with water vapor. Additional advantage is the purity of the resulting powders, because the only products of the chemical reactions are the metal (hydrous) oxide and alcohol. The particles are, therefore, free of impurities, such as various ions, normally present in solids prepared from different salts. 

Because your body uses saturated fats to synthesize cholesterol, the more saturated fats you ingest, the more cholesterol your body is able to synthesize. Unsaturated fats, by contrast, are not ideal starting materials for cholesterol synthesis. 

Poly(vinylbenzyl chloride) (VBC) is an ideal starting material onto which a variety of functional groups can be attached through relatively simple reactions and mild reaction conditions. Functionalized polymers are of interest in a variety of applications including but not limited to fire retardants, selective sorption resins, chromatography media, controlled release devices and phase transfer catalysts. An example of the wide applicability of functionalized polymers is provided by trimethyl ammonium functionalized poly(VBC). 

Because substituted anilines are widely available, they are ideal starting materials for the synthesis of indoles. Although anilines are often the precursors of the hydrazones used in the Fischer cyclization, more direct methods for conversion of anilines to indoles would be highly desirable. Such a process would, in general, have to involve some method for specific o -substitution of the aniline derivative. In the most successful method of this type which has been developed to date, a specific rearrangement effecting o-substitution is the key to a synthetic scheme which constructs indoles from anilines via anilinosulfonium ions. The procedure, which in appropriate circumstances can be carried out without isolation of the intermediates, involves oxidation of the aniline to an A-chloroaniline, reaction with a thiomethylmethyl ketone and a weak base, followed by cyclizative condensation (equation... 

The simplest amino acid, glycine, would be an ideal starting material for the synthesis of more complicated amino acids but it does not easily form enols or enoiates. The methyl ester of the ben-zaldehyde imine has two electro n-withdra wing groups to help stabilization of the enolate and conjugate addition of acrylonitrile is now possible. The base used was solid potassium carbonate with a quaternary ammonium chloride as phase transfer catalyst. Simple hydrolysis of the alkylated product leads to the extended amino acid. 

Fell et al. (1960) and Blackburn and Lee (1963) are studjdng the amino acid sequences in a-keratose. Although this fraction is heterogeneous and therefore is not an ideal starting material, it is preferable to the complex mixture of proteins in the original fiber. A preliminary note has appeared regarding the work of Blackburn and Lee (1963), but this gives no results. 

The process described in the preceding subchapter may be considered obsolete as since the advent of industrial chromatographic separation, xylose can be obtained much more economically from sulfite waste liquor, which is an ideal starting material for the following... 

Although silylenes and disilenes bearing bulky substituents have been known for a considerable time, their synthetic potential has by no means been fully exploited. In particular, only very few routes are available for the preparation of alkyl-substituted representatives [1], Hexa-f-butylcyclotrisilane is an ideal starting material for the generation of di-/-butylsilylene 2 and tetra-/-butyldisilene 3. 

Chemically, 3-picoline is the ideal starting-material for nicotinic acid or amide the methyl group can be selectively and readily oxidized to the carboxyl derivative with few by-products or pollutants. High selectivity coupled with the low molecular weight ratio (1 1.3) compared to the end-products make picoline an attractive industrial starting-material for the production of nicotinic derivatives. 

Starting-material although MEP is produced from cheap starting-materials (ammonia and paraldehyde), the process itself produces considerable quantities of by-products and/or waste material, which have to be separated and suitably treated to avoid environmental pollution. Additionally, the carbon efficiency of the MEP conversion into niacin is at best only 0.75 (two carbon atoms are burnt off during oxidation), so that, from the green standpoint, MEP is not the ideal starting material. 

The 3,4-diamino-(5//)-2-furanones are considered ideal starting materials for synthesizing various heterocyclic compounds. An efficient synthe-... 

A photooxygenation step was also found useful for the synthesis of dehydropregnenolone acetate (16-DPA, 61) - an ideal starting material for the preparation of important steroidal drugs - from naturally occurring diosgenin (59, Scheme 2.35). ... 

Opening the oxazolidinone ring reveals a three carbon chain with one functional group on each carbon atom 217. Glycidol, available as either enantiomer, is an ideal starting material. 

The ease of formation of carbenium ions from substrates such as tertiary alcohols means these are ideal starting materials for the Ritter reaction. However, formation of such an ion at a less substituted centre is much less facile, if not impossible. There has been a large amount of work that focused on the stabilisation or promotion of carbenium ion formation at such centres. 

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