Thioglycolate, Michael addition

Compound 9 has also been obtained via nucleophilic displacements by thioglycolic acids on activated halobenzenes12,13 and Michael addition to acrylate esters14,17,18 or acrylonitriles19 with subsequent hydrolysis. 

Several structurally different diketones (acetylacetone, methyl 2-oxocyclohex-ane carboxylate) and active methylene compounds (diethyl malonate, ethyl aceto-acetate) and thiols (methyl thioglycolate) underwent clean, fast, and efficient Michael addition with methyl vinyl ketone, acrolein, and methyl acrylate over NaY and Na beta zeolites [88] in high yield (70-80%). The reactions were performed in the absence of solvent, at room temperature, with 1 g catalyst per mmol donor. When HY zeolite was used instead of NaY formation of the desired Michael adduct was low and polymerization of Michael acceptor was the main reaction. 

Natural cinchona alkaloids were reported to promote the sulfa-Michael addition to different electron-poor alkenes as well. Catalysts 1 and 2 were employed by Pracejus et al. [11] in the moderately enantioselective additions (up to 54% ee) of benzylmercaptan to a-phthalimidomethacrylate. The same bases were found to promote the asymmetric addition of benzylmercaptan and tritylmercaptan to nitro-alkenes. Similar results were later reported with thioglycolic acid as the nucleophile [12]. Low enantioselectivities were obtained in the process catalyzed by different alkaloids such as bmcine, strychnine, and A-methyl ephedrine [11]. Catalyst 4 was successfully employed in the sulfa-Michael addition of thiophenol to maleic acid... 

Asymmetric Michael addition of optically active perhydro-l,4-oxazepin-5,7-diones, and of thioglycollic acid in the presence of a cinchona alkaloid as catalyst, to a-nitro-olefins yields y-nitrocarboxylic acids and 2-nitrothio ethers, respectively, with reasonable enantiomeric excess. Allylsilanes add to a-nitro-olefins in the presence of aluminium chloride to give unsaturated nitronic acids, which are further transformed in a Nef-type reaction to give y,5-enones (Scheme 36).Nitro-compounds are also converted into the corresponding carbonyl compounds upon treatment with base and MoOs pyHMPA, a new modified Nef reaction. 

By far most of the reports on addition reactions of hetero-nucleophiles to activated dienes deal with sulfur-nucleophiles " ° 20-t37 jjj particular in the synthesis of 7/1-sulfur-substituted steroids which, like their carbon-substituted counterparts (Section ILA), are of interest because of their ability to inhibit the biosynthesis of estrogens ° 129-137 Early investigations 120-122 concentrated on simple acyclic Michael acceptors like methyl sorbate and 2,4-pentadienenitrile. Bravo and coworkers observed the formation of a 3 1 mixture of the 1,6- and 1,4-adduct in the reaction of methyl sorbate with methanethiol in basic medium (equation 39). In contrast to this, 2,4-pentadienenitrile adds various thiols regioselectively at C-5, i.e. in a 1,6-fashion (equation 4O) 121.122, jjjg same is true for reactions of this substrate with hydrogen sulfide (equation 41), sodium bisulfite and ethyl thioglycolate. ... 

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