Competitive Silyl–Prins Cyclization versus Tandem Sakurai–Prins Cyclization: An Interesting Substitution Effect
作者:Alberto Diez‐Varga、Héctor Barbero、Francisco J. Pulido、Alfonso González‐Ortega、Asunción Barbero
DOI:10.1002/chem.201403421
日期:2014.10.20
allylsilyl alcohols without allylic substituents, the reaction gives dioxaspirodecanes, which are the products of a tandemSakurai–Prinscyclization. In contrast, allylsilyl alcohols with an allylic substituent (R2≠H) selectively provide oxepanes, thus corresponding to a direct silyl–Prinscyclization. Both types of product are obtained with excellent stereoselectivity. Theoretical studies have been performed
Multicomponent Prins Cyclization from Allylsilyl Alcohols Leading to Dioxaspirodecanes
作者:Asunción Barbero、Alberto Diez-Varga、Francisco J. Pulido
DOI:10.1021/ol402425u
日期:2013.10.18
A multicomponent reaction for the preparation of dioxaspirodecanes starting from allylsilyl alcohols was achieved. The one-pot sequence involves the sequential acid-catalyzed reaction of an allylsilyl alcohol with an aldehyde to afford an alkenediol. The subsequent Prins cyclization of the homoallylic alcohol moiety generates a tetrahydropyranyl carbocation which is intramolecularly trapped by the second hydroxyl group. The chemoselectivity of the process shows dependence on the nature of the aldehyde and the concentration of the catalyst.
Efficiency of Acid- and Mercury-Catalyzed Cyclization Reactions in the Synthesis of Tetrahydrofurans from Allylsilyl Alcohols
作者:Francisco J. Pulido、Asunción Barbero、Patricia Val、Alberto Diez、Alfonso González-Ortega
DOI:10.1002/ejoc.201200666
日期:2012.9
The scope of the acid-catalyzed and mercury-catalyzed cyclization reactions of allylsilyl alcohols is described. This methodology has been found to be an efficient approach to the synthesis of highlysubstitutedtetrahydrofurans. The stereoselectivity of the cyclization is dependent both on the substitution of the starting alcohol and on the catalyst. A plausible mechanism has been proposed that is