19980-22-4Relevant articles and documents
Stereochemical control in the synthesis of tetrahydrofurans by cyclisation of diols with [1,2]phenylsulfanyl migration
Aggarwal, Varinder K.,Eames, Jason,Villa, Maria-Jesus,McIntyre, Sara,Sansbury, Francis H.,Warren, Stuart
, p. 532 - 546 (2007/10/03)
Acid catalysed rearrangement of a series of 4-PhS-1,3-diols with toluene-p-sulfonic acid in benzene gives stereospecifically substituted 3-PhS-tetrahydrofurans in excellent yield via a [1,2]-SPh shift. We comment on the structural variation at both the migration origin and terminus on the outcome of the title reaction and define its limits.
Synthetic utility and mechanistic studies of the aliphatic reverse brook rearrangement
Linderman, Russell J.,Ghannam, Ameen
, p. 2392 - 2398 (2007/10/02)
The aliphatic reverse Brook rearrangement has been examined in detail. Transmetalation of [α-[(trialkylsilyl)-oxy]alkyl]trialkylstannanes occurs via a complex equilibrium favoring the most stable carbanion. The aliphatic reverse Brook rearrangement is driven forward by the rapid migration of silicon from O to C in a transient α-silyloxy carbanion due to the formation of the more stable lithium alkoxide. Cross-over experiments have shown that the rearrangement is an intramolecular process while incorporation of a radical trap revealed that the rearrangement does not involve radical intermediates. Studies of configurationally fixed stannanes derived from 4-tert-butylcyclohexanone concluded that the rearrangement occurs with retention of configuration. Preparation and reverse Brook rearrangement of optically active (S)-[α-[(trimethylsilyl)oxy]-hexyl]tributylstannane (98% ee) provided 1-(trimethylsilyl)hexanol in 97% ee. The synthetic utility of this method for the preparation of a variety of (α-hydroxyalkyl)trialkylsilanes from aldehydes has also been demonstrated.
A NEW PRACTICAL SYNTHESIS OF SILYL ENOL ETHERS. PART.I. FROM SIMPLE ALDEHYDES AND KETONES.
Cazeau, P.,Duboudin, F.,Moulines, F.,Babot, O.,Dunogues, J.
, p. 2075 - 2088 (2007/10/02)
A new, practical route to enoxysilanes is described from simple enolizable aldehydes or ketones, using the trimethylchlorosilane-sodium iodide-tertiary amine reagent in acetonitrile.From certain aldehydes, an onium intermediate has been isolated.A conformational study of this onium intermediate and a thermal unimolecular syn-elimination process may explain the stereoselectivity of the reaction.Such an interpretation can be extended to all the aldehydes and ketones considered.Steric factors related to the nature both of the cabonyl derivative and of the amine play a capital role for the regio- as well as for the stereo-control of the reaction.
