Thiophene alcohols esters

Rather similar was the paper [PolG36a] which also derives asymptotic formulae for the number of several kinds of chemical compounds, for example the alcohols and benzene and naphthalene derivatives. Unlike the paper previously mentioned, this one gives proofs of the recursion formulae from which the asymptotic results are derived. A third paper on this topic [PolG36] covers the same sort of ground but ranges more broadly over the chemical compounds. Derivatives of anthracene, pyrene, phenanthrene, and thiophene are considered as well as primary, secondary, and tertiary alcohols, esters, and ketones. In this paper Polya addresses the question of enumerating stereoisomers -- a topic to which we shall return later. 

Intramolecular asymmetric induction has also been used in electrochemistry as in the reduction of optically active alcohol esters or amides of a-keto [469,470] and unsaturated [471] acids and oximes [472] and in the oxidation of olefins [473]. A maximum asymmetric yield of 81% was obtained in the reduction of (5 )-4-isopropyl-2-oxazolidinone phenyl-glyoxylate [470]. Nonaka and coworkers [474,475] found that amino acid A-carboxy anhydrides were polymerized with various electrogenerated bases as catalyst to give the poly(amino acids) with high chirality in high yields. Conductive chiral poly(thiophenes) prepared by electropolymerization can be used for chiral anion recognition [476]. 

The flavour components are reported (Fedeli, 1977) to consist of hydrocarbons, aliphatic hydroxy compounds, aldehydes, ketones, ethers, furan derivatives, thiophene derivatives, esters and terpene alcohols. 

Polyphosphazenes with simple alkyl and aryl substituents directly attached to the backbone by P-C linkages can be prepared by the condensation polymerization of N-silylphosphoranimine precursors. These simple polymers can then be converted to a variety of functionalized polyphosphazenes by derivatization reactions. In this paper, the synthesis and characterization of some derivatives of poly(methylphenyl-phosphazene), [Me(Ph)P=N]and the copolymer, [Me(Ph)P=N]j [Me2P=N)y, are discussed. These polymers include grafted copolymers, water soluble carboxylated polymers, and polymers with silyl, vinyl, alcohol, ester, ferrocene, phosphine, thiophene, and/or fluoroalkyl groups. 

Pd(II) salts promote the carbonylation of organomercury compounds. Reaction of phenylmercury chloride and PdCh under CO pressure affords benzophenone (429)[387]. Both esters and ketones are obtained by the carbonylation of furylmercury(Il) chloride in alcohol[388]. Although the yields are not satisfactory, esters are obtained by the carbonylation of aryl- and alkylmercuryfll) chlorides[389,390]. One-pot catalytic carbonylation of thiophene, furan, and pyrrole (430) takes place at the 2-position via mercuration and transmetallation by the use of PdCb, Hg(N03), and CuCl2[391]. 

In a related report, ruthenium-catalyzed enantioselective hydrogenation of 3-keto esters was utilized to prepare the crucial alcohol intermediate 36 (Scheme 14.16). The required (3-keto ester 49 was readily prepared from commercial thiophene carboxylic acid 40. Hydrogenation of 49 then led to the desired (S)-alcohol 50 in quantitative yield and 90% enantiomeric excess, catalyzed by a chiral diphosphine-ruthenium complex generated in situ. Catalyst-substrate ratios used were as low as 1/20,000, rendering this approach amenable to industrial application. Alcohol 50 was then converted to known intermediate 36 in three steps and 60% overall yield. 

Thiophene-2-carbaldehyde condenses easily with ethyl acetoacetate or ethyl nitroacetate in the presence of TiCU and a tertiary organic base (pyridine or N- methylmorpholine) at 0-22 °C, giving (361) (72T663). Base-catalyzed condensation of thiophene-2-carbaldehyde with methyl (methylthio)methyl sulfoxide followed by treatment with HC1 in alcohols gives (2-thienyl)acetic esters (Scheme 114) (79BCJ2013). 

Hinsburg first reported that various a-dicarbonyl compounds (256) condensed with thiodiglycolic esters in the presence of alcoholic sodium ethoxide to give various substituted thiophene-2,5-dicarboxylic esters (257). R1 and R2 in (256) could be H, OH, alkyl, OR, aryl or carboxyl groups o-quinones will also condense. If the condensation is carried out in aqueous alcohol, as is the case when glyoxal (256 R1 = R2 = H) is used, the thiophene-2,5-dicarboxylic acid is isolated directly. Pyruvic acid gives the half-ester of (257 R1 = Me, R2 = OH). The earlier work has been reviewed (52HC(3)l). 

Thus, 5-ethyl-2-thienylthioacetic ester (167) was converted to the aldehyde-ester derivative (168) using the Vilsmeier reaction. The action of alcoholic alkoxide on (168) led to the cyclized product (169). Subsequent decarboxylation gave the thieno[2,3-6 ]thiophene derivative (71 Scheme 55) (76AHC(19)123). 

Reaction of 2-benzo[6]thienyllithium (and its 7-methyl derivative 90) with aldehydes 486,5fl4, 620 or ketones 467 483 affords a secondary or tertiary alcohol, respectively. Treatment of 2-benzo[6]thienyl-lithium with acetyl chloride gives mainly l,l-di(2-benzo[6]thienyl)-ethylene.132 Side-chain alcohols in positions other than the 2-position are most easily prepared by reaction of the appropriate benzo[6]-thienylmagnesium halide with aldehydes 460,471 or ketones,186,3o9, 349, 4 7,466,479,498 or foy reaction of a benzo[fe]thiophene aldehyde, ketone, or ester with an alkylmagnesium halide.358,427 465 The preparation of alcohols from 2- and 3-benzo[6]thienylmethyl-magnesium chloride485,528 is discussed in Section VI, D, 4. 

Esters, amides, and primary alcohols are obtained from benzo[6]-thiophene carboxylic acids by standard procedures.337 481,585 692 093,695 Acid chlorides undergo the Arndt-Eistert reaction,337,568,689 react with diethyl ethoxymagnesium malonate to give the corresponding methyl ketone,144 557 and are reduced to the aldehyde with 1 ithium tri-ferf-butoxy aluminohydride.33 7... 

Fiesselmann and Pfeiffer114 passed HCI at 0° through acetoacetic ester and thioglycolic ester in alcohol to obtain triethyl /5,/J-bis(carbo-methoxymethylthio)butyrate (169) Dieckmann condensation reportedly furnished ethyl 3,4-dihydroxy-6a-methyI-3a,6a-dihydro-thieno[2,3-ft]-thiophene-2-carboxylate (170) [Eq. (48)]. 

Hundreds of compounds have been identified in the volatile flavor components of processed foods. Hydrocarbons, alcohols, ethers, aldehydes, ketones, acids, acid anhydrides, esters, aromatic, lactones, pyrones, furans, pyridines, pyrroles, n-alkylpyrrole-2-aldehydes, pyrazines, sulfides, disulfides, thiols, thiophenes, thiazoles, trithiolanes, thialdine. ..etc. 

Food, flavors consist of numerous compounds, none of which alone is characteristic of specific food. Classes of compounds which emcompass food flavors are - hydrocarbons (aliphatic, ali-cyclic, aromatic) carbonyls (aldehydes, ketones) carboxylic acids, esters, imides, anhydrides alcohols, phenols, ethers alkylamines, alkylimines aliphatic sulfur compounds (thiols, mono-, di- and tri-sulfides) nitrogen heterocyclics (pyrroles, pyrazines, pyridines) sulfur heterocylics (thiophenes, thiazoles, trithiolane, thialidine) and oxygen-heterocyclics (lactone, pyrone, furan). Discussion will be limited to striking developments in heterocyclics. 

The Pauson Khand reaction is compatible with a wide variety of functionalities, such as ethers, alcohols, tertiary amines, thioethers, ketones, ketals, esters, tertiary amides, carbamates, and benzene, furan, and thiophen rings. Disubstituted alkynes, alkenes with bulky allylic substituents, and trisubstituted alkenes frequently afford reduced yields of products. Because of the reduced ability of sterically hindered alkenes to coordinate and undergo insertion, insertion of one or more molecules of alkyne occurs instead. 

Nearly 1000 compounds have so far been identified in the volatile constituents of meat from beef, chicken, mutton and pork (6). The largest number of volatiles has been determined in beef and these were representative of most classes of organic compounds. Hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, esters, lactones, ethers, sulfur and halogenated compounds as well as different classes of heterocyclic substances (Figure 1) namely furans, pyrldlnes, pyrazines, pyrroles, oxazol(in)es, thiazol(in)es, thiophenes were present in cooked meat flavor volatiles as shown in Table I. Many of these compounds are unimportant to the flavor of meat and some may have been artifacts (16). 

Flavor Components. Olive oil volatiles contain at least 100 compounds (33-37) in several categories hydrocarbons (5 compounds), aliphatic alcohols (13 compounds), terpenic alcohols (4 compounds), aldehydes (27 compounds), ketones (8 compounds), ethers (2 compounds), furans (3 compounds), thiophenes (6 compounds), and esters (29 compounds). 

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