Methyl 2-chloroacrylate

With a,p-dihalo- or a-halo-a,p-unsaturated carbonyl derivatives A significant number of examples exist in which a,P-dihalogenated carbonyl derivatives undergo reactions with thioglycolates in the presence of base to produce thiophenes. " The reactions have been shown to occur through intermediate a-halo-a,P-unsaturated carbonyl derivatives produced by the elimination of HX. Thus the use of a-halo-a,P unsaturated carbonyl systems in place of the a,P-dihalocarbonyl compounds was found to efficiently provide thiophenes upon reaction with thioglycolates. In a modification of the work of Fiesselmann, readily accessible methyl-2-chloroacrylate 23 and 2-chloroacrylonitrile 24 have been used in this sense to provide 25 and 26, respectively. 

An additional chiral center can be introduced at C, by use of methyl 2-chloroacrylate. 

Compound (80), prepared from 2-methylcyclopentane-l,3-dione and methyl 2-chloroacrylate followed by the sequence (76)-> (77)-> (78)- (79) (resolved)— (80), combined with (71) (prepared from m-methoxyphenylstyrene and diborane) to form the seco-steroid (82)/ Acetic anhydride-toluene-p-sulphonic acid then cyclized this stereoselectively to furnish the triacetate (83) which on saponification gave the triol (84). Interestingly, this compound reacted with toluene-p-sulphonic acid in alcohol to produce, by dehydration and change of configuration at C-14, the compound (85), which served as a source of various 8a-oestrone compounds. Compound (84) on treatment with boron trifluoride etherate underwent pinacol transformation in preference to dehydration to yield the ketone (86) this ketone was correlated with the known compound (87). 

The tetracarbonyl iron complex of methyl acrylate, methyl 2-chloroacrylate ° and methyl crotonate react in a similar fashion. Although the resulting jj -alkyliron complexes are stable (requiring treatment with trifluoroacetic acid followed by a oxidant to free the organic group from the iron), they are not well characterized. 

Much of the world s cysteine is isolated from keratin, mostly obtained in the form of hair. The process, which is based on an acid hydrolysis of the protein, is smelly, and it produces waste products which are difficult to treat. It is progressively being replaced by an enzymatic synthesis which once again couples a stereospecific hydrolysis with a racemisation process. Methyl-2-chloroacrylate is converted into DL-amino-A2-thiazoline-4-carbo-xylate, and both enantiomers of this intermediate are then hydrolysed by an enzyme from Pseudomonas thiazolinophilum or Sarcina lutea directly to L-cysteine. The necessary racemisation occurs spontaneously during the reaction (Scheme 6.10). 

Poly(methyl methacrylate-co-methyl-2-chloroacrylate) Chloroform SEC, u-styragel 561... 

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