Stereochemically controlled synthesis of 1,8-dioxaspiro[4.5]decanes and 1-oxa-8-thiaspiro[4.5]decanes by phenylsulfanyl migration

Asymmetric synthesis of tetrahydrofurans by competitive [1,2]-phenylsulfanyl (PhS) migrations under thermodynamic control

“…The second pair of triols (6 and 9) had a cyclohexane ring present and the final set (triols 7 and 10) had a THP ring present in order that we could prepare some unusual dioxaspirocycles that are not trivial to prepare by other routes. 7 The triols could be synthesised asymmetrically: Sharpless asymmetric dihydroxylation (AD) 8 of a homoallylic ketone being the key step in our route to these compounds.…”

Stereochemical control in the synthesis of tetrahydrofurans by cyclisation of diols with [1,2]-phenylsulfanyl migration

“…We have observed stereospecific C-O, 1 C-N 4 and C-S 5 bond formation to give diastereoisomeric and enantiomerically 6 pure spirocyclic heterocycles and allylic derivatives. 7,8 We now report on the cyclisation of a new acyclic class of diol with structural variation at both the migration origin and terminus. We discuss stereochemical features (relative stereochemistry, Baldwin's rules 9 and the Thorpe-Ingold effect 10,11 ) which affect the observed mode and the efficiency of cyclisation of such [1,2]-SPh processes.…”