Preparation of (
<i>Z</i>
)‐Alk‐2‐ene‐1,5‐diols by the Titanocene(II)‐Promoted Cyclization of Thioacetals Possessing a Terminal Carbon−Carbon Double Bond
Titanocene(II)-promoted ring-closing metathesis of the titanium carbene complexes prepared from [2,2-bis(phenylthio)ethyl](but-3-enyloxy)dimethylsilanes or dimethyl(prop-2-enyl)silyl ethers of 3,3-bis(phenythio)propanols gave seven-membered cyclic unsaturated silyl ethers. Oxidative cleavage of a silicon−carbon bond of the cyclic silyl ethers resulted in olefinic diols, with high Z stereoselectivity.