N‐Heterocyclic Carbene‐Mediated Organocatalytic Transfer of Tin onto Aldehydes: New Access to α‐Silyloxyalkylstannanes and γ‐Silyloxyallylstannanes

Abstract

A new, highly efficient and mild N-heterocyclic carbene (NHC)-mediated organocatalytic procedure for the transfer of tin from tributyl(trimethylsilyl)stannane (Bu 3 SnSiMe 3 ) onto aldehydes for the preparation of a-silyloxyalkylstannanes and g-silyloxyallylstannanes has been developed.

Organocatalytic Reactions Enabled by N-Heterocyclic Carbenes

“…section ). A similar reaction was reported by Commeiras, Parrain and co-worker, who activated tributyl­(trimethylsilyl)­stannane for the 1,2- or 1,4-addition of tributyl tin to aldehydes or enals . Aliphatic, heteroaromatic, and electron-rich aryl aldehydes proceed in good yields (85–100%); however, electron-deficient aryl aldehydes are much less consistent (often resulting in no reaction).…”

“…A similar reaction was reported by Commeiras, Parrain and co-worker, who activated tributyl(trimethylsilyl)stannane for the 1,2-or 1,4addition of tributyl tin to aldehydes or enals. 274 Aliphatic, heteroaromatic, and electron-rich aryl aldehydes proceed in good yields (85−100%); however, electron-deficient aryl aldehydes are much less consistent (often resulting in no reaction). Acrolein and its derivatives also participate, generating the 1,4-tin addition adduct as the only observable addition product, while β-substituted enals favored 1,2-addition.…”

Synthesis of Arylglycine and Mandelic Acid Derivatives through Carboxylations of α-Amido and α-Acetoxy Stannanes with Carbon Dioxide

“…To our knowledge, there have been no reports on a general carboxylation of α-alkoxy stannanes with CO 2 promoted by a fluoride ion. First, several α-hydroxy stannanes having different protecting groups (PGs) were prepared from benzaldehyde ,, and subjected to carboxylation (Table ). Among potential candidates such as acetyl, ethyl carbonyl, MOM, and TMS, the use of acetyl protection was most effective, giving high conversion even at 60 °C within 3 h. Protection other than that with the TMS group is necessary; under the conditions examined, retro-stannylation occurs, affording benzaldehyde starting material exclusively.…”