Studies on Instructive Construction of <i>exo</i>-Olefin Terminated Five- and Six-Membered Nitrogen Heterocycles: SmI<sub>2</sub>-Mediated Intramolecular Cyclization of Haloalkynals
pyrrolidine and piperidine frameworks was developed by employing SmI2-mediated intramolecular radical cyclization of haloalkynaks. The radical cyclization affording 2,3-disubstituted pyrrolidines and piperidines proceeded in a highly stereoselective manner. However, decreasing stereoselectivety was observed in the preparation of 2,4-disubstituted pyrrolidine and 3,4-disubstituted piperidinederivatives in the
作者:Chun-Hua Yang、Meng Han、Wenyan Li、Ningning Zhu、Zhenzhen Sun、Junjie Wang、Zhantao Yang、Yue-Ming Li
DOI:10.1021/acs.orglett.0c01685
日期:2020.7.2
Direct intramolecular aminoboration of sulfonamidoallenes was realized using BCl3 as a boron source. The reactions benefited from the interaction between BCl3 and sulfonamides and provided a variety of borylvinyl heterocycles in good isolated yields. When chiral substrates were involved in the reactions, high stereoselectivity was observed, as can be ascertained by single-crystal X-ray diffraction
Diastereoselective Syntheses of Functionalized Five-Membered Carbocycles and Heterocycles by a SmI<sub>2</sub>-Promoted Intramolecular Coupling of Bromoalkynes and α,β-Unsaturated Esters
作者:Kazunori Takahashi、Toshio Honda
DOI:10.1021/ol101034s
日期:2010.7.2
An intramolecular coupling of bromoalkynes with alpha,beta-unsaturated esters afforded functionalized five-membered carbocycles and heterocycles with high diastereoselectivities in excellent yields. The vinyl bromides newly generated as the products serve as adequate intermediates for further chemical modification.