Cytotoxic compounds. Part XII. Some 3-arylthiopropane-1,2-diols and 2-arylthiopropane-1,3-diols. Rearrangement of the 1,3-dimethanesulphonates to the 1,2-isomers
Abstract
Syntheses of the title diols, their acetates, and their methyl ethers are described, where the aryl group is p-chloro-p-methoxy-, p-methylthio-, and 2,4-dinitro-phenyl. Rearrangement through an episulphonium ion-pair occurs in the preparation of a dimethanesulphonate from 2-(p-methoxyphenylthio)propane-1,3-diol, the product being the derivative of the isomeric 1,2-diol. Unrearranged dimethanesulphonates were obtained from all the other diols, but the 1,3-dimethanesulphonates where the aryl group is phenyl, p-chlorophenyl, and p-methylthiophenyl undergo rearrangement to the 1,2-isomers in boiling acetone. In methanol, solvolysis of the 1,3-dimethanesulphonates occurs much more rapidly than with the 1,2 isomers.
The two geometrical isomers of the O-toluene-p-sulphonate of 1,3-O-benzylideneglycerol have been separated and identified. Some of the aryl sulphides, obtained by displacement reactions on this sulphonte with aryl thiols, have also been obtained as individual stereoisomers.
The 1H n.m.r. spectra of the diols and of their derivatives are tabulated.