Dithioacetic acid Subject

Among the facts supporting this mechanism (which is an A-Se2 mechanism because the substrate is protonated in the rate-determining step) are (1) lsO labeling shows that in ROCH=CH2 it is the vinyl-oxygen bond and not the RO bond that cleaves 497 (2) the reaction is subject to general acid catalysis 498 (3) there is a solvent isotope effect when D2O is used.498 Enamines are also hydrolyzed by acids (see 6-2) the mechanism is similar. Ketene dithioacetals R2C=C(SR )2 also hydrolyze by a similar mechanism, except that the initial protonation step is partially reversible.499 Furans represent a special case of enol ethers that are cleaved by acid to give 1,4 diones. Thus... 

Fig (19) Octalin ketal (163) is converted to kete dithioacetal (164) by the cleavage of ketal function and condensation with carbon disulfide and methyl iodide. Subjection of (164) to the action of dimethylsulfonium niethylide and acid hydrolysis leads to the formation of unsaturated lactone (165).lts furan silyl ether derivative is caused to undergo Diets-Atder reaction with methyl acrylate to obtain salicyctic ester (166) which is converted by standard organic reactions toabietane ether (167). It is converted to aiiylic alcohol (168) by epoxidation and elimination. Alcohol (169) obtained from (168) yields orthoamide which undergoes transformation to amide (170). Its conversion to the previously reported intermediate has been achieved by epoxidation, elimination and hydrolysis. 

O-Alkyl a-(trimethylsilyl)thioacetates and S-alkyl a-(trimethylsilyl)dithioacetates 119 can be deprotonated and subjected to Peterson reactions with aldehydes to give the a,jS-unsaturated thiocarboxylic acid O-esters and dithiocarboxylic acid S-esters 120, respectively (Scheme 2.72). The alkenes are obtained -selectively [200]. 

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