Saturated Thioacetals and Selenoacetals

The synthesis of the mono-S -oxo-dithioacetal moiety of the antibiotic sparso-mycin has been accomplished, starting from iV-benzyloxycarbonyl-L-cysteine. 0,5-Acetals can be prepared by treatment of ct-(phenylthio)alkylboranes with 

Cravador, A. Krief, and L. Hevesi, J. Chem. Soc., Chem. Commun., 1980,451. 

Kaneko, K. Kawabata, and E. Fujita, Tetrahedron Lett., 1978, 5021. 

AT-chlorosuccinimide in MeOH (PhSCHRBRj - PhSCHROMe)/ methanolysis of 5-monomethyl dithioacetal fluorosulphonates, and addition of an alkyl-lithium to thiono-esters. Quantitative studies have been reported for an interesting variation on the simplest preparation, in which hemithioacetals exist in equilibrium with an aldehyde and a mixture of two thiols.  

The conclusion to uses of dithioacetals and selenium analogues in synthesis is usually a form of hydrolysis to give an aldehyde or a ketone. New dethio-acetalization studies describe uses of NO+ HS04, of either NaNOj or NaNOj with TFA, or of BF4 , of isoamyl nitrite, or of Me2 Br Br. A 

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