Alkylidenation of Carbonyl Compounds with gem-Dizincioalkanes Mediated with Titanium Dichloride

Abstract

Olefination of carbonyl compounds with gem-dizincioalkanes, bis(iodozincio)methane, 1,1-bis(iodozincio)ethane, and bis(bromozincio)methyltrimethylsilane, afforded the corresponding olefins in good to excellent yields.

Structure and reactivity of bis(iodozincio)methane solution

“…While these procedures had used in situ formation of methylene dizinc species during methylenation reaction, we showed the preparation of methylene dizinc as THF solution from diiodomethane and zinc dust in the presence of lead catalyst [13]; we analyzed its structure by 1 H NMR ( Fig. 1) [14,15]. We then performed several types of molecular transformations using this THF solution of methylene dizinc [16].…”

Molecular Transformations Using Bis(iodozincio)methane–The Role of Chelation in Main Group Organometallic Chemistry

“…12 In 1994, Utimoto and Takai demonstrated that the presence of lead in a commercially available pyrometallurgy zinc powder (0.040.07%) is a crucial factor for the fast reduction of diiodomethane to the gem-dizinc species. 13 Later we reported a general procedure to prepare a THF solution of 1, 14 and characterized its structure in THF.…”

Carbon–Carbon Bond Forming Reactions Mediated by Organozinc Reagents

“…Insertion of zinc into the carbon-halogen bond of organozinc carbenoids is accelerated by the presence of a catalytic amount of Pb(II) salts [40]. By this means, several 1,1-(biszincio)alkane reagents such as 14, 15 [41], or 16 [42] can be prepared (Scheme 4.4). The commercially available Nysted reagent 17 is also prepared through zinc insertion with zinc-lead couple [43].…”