Technix540

Something like this perhaps?

Hi John, thanks for your reply. I thought HSiPr was a thiol with an isopropyl group (HSR)?. In the presence of base, the most acidic H should get deprotonated (alfa-position either left or right of the carbonyl) Or perhaps the base deprotonates the thiol thus increasing its nucleophilicity. The gamma-position is attacked by the thiol since the delta-position is blocked due to sterics which would arise from the two isopropyl groups. Stereochemistry, since the top face is hindered by the isopropyl group (wedged line) the attack could be made from the bottom face (dashed line)?

Need to know exact mechanism and absolute stereochemistry? This is a beta-gamma unsaturated ketone and we haven't discussed them in class at all. I might be a little tired in the head (exam coming up), but this can't simply be a protonation of the double bond, followed by a nucleophilic attack on the formed carbocation could it? Does anybody have any tips on what type of reaction this is?