Direct synthesis of trimethylvinylstannanes from aldehydes

Carbon−Carbon Bond Formations Involving Organochromium(III) Reagents

“…When the Takai−Utimoto olefination method is applied to R 3 SnCHX 2 as the substrates, the stereoselectivity of the resulting alkenylstannanes depends, to some extent, on the substituents R on the tin moiety (Table ). While Bu 3 SnCHBr 2 generally affords the ( E )-isomer exclusively, Me 3 SnCHBr 2 usually leads to ( E ):( Z ) mixtures (69:31−88:12); however, the yields obtained are higher with the latter reagent . In some cases, protodestannylation of the alkenylstannanes formed cannot be completely suppressed. , THF containing 1 equiv of DMF relative to CrCl 2 was reported to be the best reaction medium in terms of stereoselectivity .…”

Hydroxyl-Assisted Carbonylation of Alkenyltin Derivatives: Development and Application to a Formal Synthesis of Tubelactomicin A

“…The methoxycarbonylation of the silyl ether derived from 24 also proceeded nicely to furnish the required trisubstituted enoate 25 in good yield. In order to exactly match fragment 16 previously used in the literature, , 25 had to be elaborated in a stepwise manner, which proceeded uneventfully, including the final Takai-type olefination with formation of the terminal alkenylstannane moiety. , With only 14 steps, this approach to compound 16 is considerably shorter than the existing route (25 steps) , and relies on the power of homogeneous catalysis in its key steps. We like to emphasize that the sequence could be shortened by several more steps if one were to accept a slightly different protecting group pattern, which would, almost certainly, also allow tubelactomicin A to be reached in the end.…”

Asymmetric Synthesis of 2-Acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)imidazoles

“…The related trimethylstannanes 13a and 13b were directly prepared from their respective aldehydes, 4a and 4b , in good yields (80−85%) and high stereoselectivity (( E ):( Z ) ca. 90:10) using trimethyl(dibromomethyl)stannane (Me 3 SnCHBr 2 ), lithium iodide, and chromium(II) chloride …”