Asuncion Barbero

The stannyl–cupration of acetylenes and the reaction of the intermediate cuprates with electrophiles as a synthesis of substituted vinylstannanes

Stannyl–cupration of acetylenes followed by electrophilic attack with a variety of electrophiles gives vinylstannanes.

Multicomponent prins cyclization from allylsilyl alcohols leading to dioxaspirodecanes.

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.

Functionalised Allylsilanes from Silylcopper Reagents and Allene. A Useful Strategy for Cyclopentane Annulations

Abstract Silylcupration of allene using phenyldimethylsilylcopper or t-butyldiphenylsilylcopper followed by reaction with α,β-unsaturated acyl chlorides, aldehydes or ketones affords allylsilane-containing divinyl ketones and oxoallylsilanes, respectively. They undergo highly stereocontrolled silicon-assisted intramolecular cyclizations when treated with protic or Lewis acid leading to cyclopentane ring-formation.

Ring-formation from allyl- and vinylstannanes initiated by treatment with butyl-lithium

Abstract The allylstannane 1 and the vinylstannanes 3 , 5 and 7 cyclise when treated with butyl-lithium.

Synthesis of vinylsilanes by silyl-cupration of acetylenes using tert-butyldiphenylsilyl-cuprate reagents

The tert-butyldiphenylsilyl-cuprate 2 reacts with acetylenes 1 and 5–10 to give vinyl-cuprates 3 and 11, which react with electrophiles to give the vinylsilanes 4 and 12–17 carrying the relatively hindered and hence unreactive tert-butyldiphenylsilyl group. In comparative tests, the tert-butyldiphenylsilyl group shows some properties that are usefully different from those of relatively unhindered silyl groups and others that are similar.

Competitive Silyl–Prins Cyclization versus Tandem Sakurai–Prins Cyclization: An Interesting Substitution Effect

Two different mechanism pathways are observed for the reaction of allylsilyl alcohols 1 and aldehydes in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf). In the case of allylsilyl alcohols without allylic substituents, the reaction gives dioxaspirodecanes, which are the products of a tandem Sakurai-Prins cyclization. In contrast, allylsilyl alcohols with an allylic substituent (R(2)≠H) selectively provide oxepanes, thus corresponding to a direct silyl-Prins cyclization. Both types of product are obtained with excellent stereoselectivity. Theoretical studies have been performed to obtain some rationalization for the observed stereoselectivity.

Stannyl-cupration of acetylenes and the reaction of the intermediate cuprates with electrophiles as a synthesis of substituted vinylstannanes

Stannyl-cupration of acetylenes followed by electrophilic attack with a variety of electrophiles gives E-vinylstannanes. These can be used either to form acetylenes, thus achieving overall the addition of an ethynyl group, or to form carbon–carbon bonds in Stille reactions.

Allylstannanes and vinylstannanes from stannylcupration of C–C multiple bonds. Recent advances and applications in organic synthesis

The stannylcupration of allenes and alkynes has emerged as a powerful tool for the synthesis of allyl- and vinylorganostannanes. The regio- and stereoselectivity of this reaction depends upon the nature of the cuprate, the temperature and the structure of the allene or alkyne. The versatility and synthetic scope of the tin-synthons thus obtained is very wide. These intermediates have been employed as precursors in the key step of the stereoselective synthesis of many natural products, heterocycles or conjugated polyenes. This tutorial review shows a general survey of the recent advances in this area together with the contribution of our lab to this field.

The synthesis of allylstannanes and, vinylstannanes by the stannyl-cupration of allenes

Stannyl-cupration of allenes followed by electrophilic attack gives allyl- and vinylstannanes with a variety of substitution patterns; the regiochemistry of the reaction depends upon the temperature and the nature of the stannyl-cuprate reagent.

Silylcupration of allenes followed by reaction with enones. A new strategy for the synthesis of methylenecyclopentanols

Abstract Silylcupration of allene using phenyldimethylsilyl-copper followed by conjugated addition to α,β-unsaturated ketones affords oxoallylsilanes with different substitution patterns. When the former oxoallylsilanes are treated with a Lewis acid they undergo highly stereoselective allylsilane terminated cyclization leading to mono-, bi-, and tricyclic methylenecyclopentanols.