Synthesis of substituted 1,4-oxathianes. Mechanistic details of diethoxytriphenylphosphorane and triphenylphosphine/tetrachloromethane-promoted cyclodehydrations and carbon-13 NMR spectroscopy
A simple and highly efficient synthesis of beta, beta'-dihydroxy sulfides has been achieved by ring opening of epoxides with mercaptoethanol using catalytic amount of benzyltrimethylammonium hydroxide (Triton B) under solvent-free conditions. Excellent regioselectivity was found for aliphatic unsymmetrical epoxides, with nucleophilic attack at the less-hindered carbon atom of the epoxide. However, this regioselectivitywas not observed for styrene oxide and a mixture of two isomers was obtained. This process was also regio- and chemo-selective as illustrated using epichlorohydrin with two epoxide ring positions and mercaptoethanol with two functional groups (SH and OH).[GRAPHICS].1a-e 2ae(1)(alpha) 2e(2)(beta)R = CH3(a) ; C2H3(b) ; CICH2(c) ; PhOCH2(d) ; ph(e).
MURRAY W. T.; KELLY J. W.; EVANS S. A., JR., J. ORG. CHEM., 52,(1987) N 4, 525-529