Unsaturated carboxylic esters alkylation

The cyclopropane cyclizations by elimination of triflinic acid (CF3S02H) are readily effected by basic treatment of triflones (trifluoromethyl alkyl sulfones) with activated /-protons (equations 46 and 47)39. The cyclopropane diesters 45 are formed on treatment of 44 with potassium hydride in DMSO or sodium methoxide in methanol (equation 48). In contrast, the monoester 46 failed to give the desired cyclopropane40. Addition of carbanions derived from /f, y-unsaturated phenyl sulfones to a, /i-unsaturated carboxylic esters and subsequent elimination of benzenesulfinate ion give cyclopropanes possessing the unsaturated side chain and the ester function in trans positions (equation 49)41. 

Keywords alkyl 2-halocarboxylate, unsaturated carboxylic ester, radical addition, lactone... 

The ate-complexes (34) also react with benzylic halides aroyl chlorides allyl halides and proj r l halides to afford the (x>rr ponding products, respectively (Eq. 75). (E)-a,P-Unsaturated carboxylic esters can also be obtains by the reaction of such borate complexes with ethyl propiolate The same type of reaction between copper(I) methyltrialkylborates and l-(l-pyrrolidinyl)-6-chloro--1-cyclohexene gives the corresponding alkylation products which are readily hydrolyzed to 2-alkylcyclohexanone... 

Reactions between diethyl hydrogenphosphonate and ArX (X = I or Br) to give diethyl arylphosphonates have been carried out in the presence of a phase transfer catalyst. Bis(trimethylsilyl) phenylphosphonite reacts with alkyl halides to give [(ar)alkylphenyl]phosphinic derivatives, and it also adds to a,P-unsaturated carboxylic esters (as well as to nitriles and amides) to give (2-functionalized-l-alkyl)phosphinic derivatives. ... 

The reaction was successfully applied to both electron-rich and electron-poor 4-nitrophenyl carboxylates among them, the conversion of the electron-deficient esters was found to be faster and more efficient. Many functional groups are tolerated on both the side of the carboxylic ester (halo, keto, formyl, ester, cyano, nitro and protected amino groups, heterocyclic and a,-unsaturated carboxylic esters) and of the alkene (electron-rich alkyl-substituted alkenes, electron-poor acrylate derivatives, trimethylvinylsilane as an ethylene surrogate). The cinnamate derivatives could become particularly useful substrates, since the availability of the synthetically equivalent vinyl halides is rather limited. In analogy to conventional Mizoroki-Heck chemistry, linear (Zi)-substituted alkenes are predominantly but not exclusively obtained. Selected examples are shown in Table 4.1. 

Aqueous, removable, pressure-sensitive adhesive compositions, useful for high-performance applications, comprise a mixture of a copolymer of alkyl (meth)acrylate and N-substituted (poly)amide of (meth)acrylic acid and a copolymer of alkyl (meth)acrylate and ethylenically unsaturated carboxylic acid, where at least one of the copolymers is an emulsion copolymer. Polyoxyalkyl-enes and phosphate esters may be used as surfactants [234]. 

Metallated 1-ethoxy-1,3-dienes 697 and 712, obtained from the corresponding acetals by means of the LICKOR base, have been treated with alkyl halides, epoxides, carbonyl compounds, carbon dioxide and carboxylic esters affording ( )-l-substituted 1-ethoxy-1,3-dienes and, after hydrolysis, a,P-unsaturated carbonyl compounds1007-1010 (Scheme 186). Intermediates 697 and 712 have been transformed into the corresponding vinyl stan-nanes, which were submitted to Stille couplings with iodobenzene and benzoyl chloride823. 

Under typical Birch reduction conditions a,P-unsaturated aldehydes, ketones and carboxylic esters are reduced to enolates, which can be trapped regiospecifically by reactive alkylating agents or other electrophiles ... 

The Potassium complex of I8-Crown-6 or Potassium Naph-thalenide effects ring-opening to give acetates or their alkylated derivatives in good yield (eq 3). Treatment of the reaction mixture obtained from p-methyl-p-propiolactone and potassium-18-crown-6 with hydrochloric acid or alkyl halides gives the acetate (S) or its alkylated derivative (6), respectively. The a,3-unsaturated carboxylic acid (7) or its ester (8) is formed by the action of the potassium naphthalenide-18-crown-6 complex. ... 

Michael additions of nitromethane. Italian chemists were able to effect Michael addition of nitromethane to z,/ -unsaturated carboxylic acid esters with catalysis by lelramethylguanidine. Yields of 1 1 adducts (1) are in the range 50-85 % when R or R are alkyl or aryl groups. If R and R are H, I 2 adducts (2) are also formed in substantial amounts. 

Although Smh is more chemoselective than traditional dissolving metal reagents, it does react with sulfoxides, epoxides, the conjugated double bonds of unsaturated ketones, aldehydes and esters, alkyl bromides, iodides and p-toluenesulfonates. It does not, however, reduce carboxylic acids, esters, phosphine oxides or alkyl chlorides. In common with most dissolving metal systems, ketones with an a-hetero substituent suffer loss of the substituent rather than reduction of the carbonyl group. ... 

Bis[4-methoxyphenyl] dicyanomethylidene tellurium did not react with benzaldehyde. Dibutyl ethoxycarbonylmethylidene tellurium and aliphatic aldehydes, aromatic aldehydes, cycloalkanones, dialkyl ketones, alkyl aryl ketones, and diphenyl ketone combine to yield a,jS-unsaturated carboxylic acid esters predominantly in the ( )-form". Dibutyl cyanomethylidene and dibutyl benzoylmethylidene tellurium react similarly with benzal-dehydes and ketones . 

Acylation of a simple thiol with an alkyl carboxylate is not a very suitable method for preparation of S-alkyl thiocarboxylates. Transesterification is, however, possible if either the thiol or the carboxylic ester is activated. The enhanced reactivity of boron, aluminum and silicon thiolates has been utilized for the synthesis of a large variety of thiocarboxylic S-esters, including hydroxy derivatives (from lactones). a,P-Unsaturated thiol esters, e.g. cinnamoyl or 2-butenoyl derivatives, are also accessible. Michael addition, an undesirable side reaction of thiols, is completely avoided if alkyl trimethylsilyl sulfides ortris(arylthio)boranes are applied. ... 

Formation of a double bond between carbon and a heteroatom or between two heteroatoms can be accomplished by a hetero retro-Diels-Alder reaction. Aldehydes, ketones and carboxylic esters can be obtain by this retrodiene process. A series of a,3-unsaturated aldehydes (152) was prepared by Funk using the facile bis-hetero retro-Diels-Alder reaction of 4-alkyl-4//-1,3-dioxins (151) as shown in equation (66). This retrodiene process involves exceptionally mild conditions, refluxing in toluene, in oMer to unmask the a, -unsaturated aldehyde. The diversity of this process is illustrated by the partial list of reactions shown.The same mild conditions can be used to prepare a, -unsaturated ketones by reflux-... 

The reactions of metailated 2-methyloxazolines with carbonyl compounds to provide adducts constitute the key step in a general procedure for the conversion of carbonyl compounds into 3-hydroxy carboxylic acids and esters or their a,3-unsaturated counterparts (Schemes 21-26). o For example, reaction of the lithiated derivative of (54) with carbonyl compounds provides the adducts (55) in high yield (Scheme 21). Subsequent acid-catalyzed hydrolysis provides the unsaturated carboxylic acids (56) depending upon the severity of the reaction conditions, acid-induced ethanolysis can be performed on the adducts (55) to provide either the unsaturated esters (57) or the 3-hydroxy esters (58) in good yields (Table 7). The main limitation of the method is that extensive retroaldolization occurs upon attempts to hydrolyze adducts (55 R = alkyl), so a-alkyl-3-hydroxy esters and acids do not appear to be accessible. 

Diastereomeric excesses as high as 84% were achieved for the photocycloaddition of methyl 3-oxo-l-cyclohexene-l-carboxylate to 2,/i-unsaturated homochiral ketals lla-c76. As the size of the ester alkyl group in the tartrate auxiliary increases from methyl to isopropyl a stepwise increase in the de values is obtained. 

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