A Convergent, Stereoselective Route to Trisubstituted Alkenyl Boronates
作者:Jean Michalland、Samir Z. Zard
DOI:10.1021/acs.orglett.1c03022
日期:2021.10.15
A modular, stereoselectiveroute to trisubstituted (Z)-alkenyl (MIDA)boronates is described, consisting of the radical addition–fragmentation of dithiocarbonates to 2-(MIDA)boronyl-3-(2′-fluoro-pyridyl-6′-oxy)-alkenes. The bulky (MIDA)boronate ensures a highly stereoselective fragmentation that is enhanced by the poor stabilization of the radical adjacent to the tetravalent boron atom. The vinyl boronate
The gold-catalyzed hydration reaction of haloalkynes is highly regioselective producing 2-halomethylketones as the sole products. Herein, we document a drastic fluorineeffect where the reaction of 1-halo-3,3-difluoroalkynes as substrates leads to a complete reversal of selectivity and produces 3,3-difluoroesters as the unique products.
The consecutive ring-closing enyne metathesis of allylsilyl propargyl ethers with Grubbs’ ruthenium-alkylidene catalyst, followed by rhenium oxide mediated 1,4-elimination of the Si-O moiety from the siloxenes, provides [3]- and [4]dendralenes in good yields.
(4 + 2) Annulation of Cl<sup>–</sup>NH<sub>3</sub><sup>+</sup>CH<sub>2</sub>SiMe<sub>2</sub>CH<sub>2</sub>Cl and Propynones for the Synthesis of 1,3-Azasilinones
作者:Chang Ma、Yu Fan、Chunmei Zheng、Lu Gao、Wanshu Wang、Bowen Ke、Zhenlei Song