Halogenated salt assisted Cu-catalyzed asymmetric 1,4-borylstannation of 1,3-enynes: enantioselective synthesis of allenylstannes

Abstract

An enantioselective 1,4-borylstannation of 1,3-enynes employed a chiral sulfoxide phosphine (SOP)/Cu complex as a catalyst, and the desired products, chiral allenylstannes, were first synthesized by asymmetric catalysis with satisfactory yields and enantioselectivies.

Stereodivergent Synthesis of Tertiary Fluoride-Tethered Allenes via Copper and Palladium Dual Catalysis

“…Although Pd-catalyzed hydrofunctionalization of conjugated enynes was discovered as an efficient route for the preparation of allenes by Yamamoto et al. decades ago, the corresponding enantioselective processes were recently realized by the Malcolmson and Tsukamoto groups independently. − In contrast, a more complex diastereoselective process using a prochiral nucleophile to tether chiral allenes to another stereogenic center has not yet been explored.…”

Palladium-Catalyzed Linear Hydrothiocarbonylation of Unactivated Terminal Alkenes: Synthesis of Aliphatic Thioesters

“…Considering the weak coordination ability of unactivated alkenes and toxic effect of thiols to metals, excess alkene 1a (1.5 equiv) was employed. In the presence of p -TsOH hydrate ( p -TsOH·H 2 O) (10 mol %) and 4- tert -butylbenzene-1,2-diol (8 mol %), the reaction was carried out in CHCl 3 at 0 °C for 24 h with a catalyst system consisting of sulfoxide phosphine ( rac -SOP)/Pd 2 dba 3 (5 mol % Pd). Linear 3aa thioester product was achieved in a moderate NMR yield (52%, based on 2a ), and no branched thioester or thioether was detected in this reaction.…”

Recent advances in the metal-catalyzed asymmetric synthesis of chiral allenes

“…Later, the same group realized the first asymmetric synthesis of chiral allenylstannes through halogenated salt assisted Cu-catalyzed 1,4-borylstannation of 1,3-enynes (Scheme 7B). 21 Allenylstannes possessing various functional groups were afforded in moderate to good yields with good enantioselectivities. This transformation proceeded through a similar transmetalation process via transition state 45 .…”