Linear and Angular Heteroacenes from Double-Electrophilic Cyclization (DEC) and DEC-Reductive Elimination of Diynes
摘要:
Linear and angular heteroacenes are prepared from terminal alkynes bearing tethered nucleophiles in two steps. Linear heteroacenes are formed from the homocoupling of these alkynes followed by reaction with a double electrophile (ECl2) to induce a tricyclization reaction cascade involving double-electrophilic cyclization (DEC). Related angular heteroacenes are formed from the prior substitution of the chloro groups in ECl2 with the same terminal alkyne followed by reaction with AuCl3 to produce a DEC-reductive-elimination (DECRE) reaction.
MPHT-Promoted Bromocyclization of ortho-Substituted Arylalkynes: Application to the Synthesis of 2-Substituted 3-Bromobenzofurans and -Benzo[b]thiophenes
A convenient and general approach to the synthesis of 2‐substituted 3‐bromobenzofurans and ‐benzothiophenes was developed. The procedure is based on the cyclization of ortho‐substituted arylalkynes in the presence of N‐methylpyrrolidin‐2‐one hydrotribromide (MPHT) as a soft and easy‐to‐handle electrophilic brominating reagent. Under mild reaction conditions, MPHT promoted the bromocyclization of various
Cascade Annulation of 2-Alkynylthioanisoles with Unsaturated α-Bromocarbonyls Leading to Thio-Benzobicyclic Skeletons
作者:Yuzhen Gao、Pengbo Zhang、Gang Li、Yufen Zhao
DOI:10.1021/acs.joc.8b02001
日期:2018.11.16
A protocol of Cu-catalyzed annulation of phenylethynylsulfanes with unsaturated alpha-bromocarbonyls for the construction of thio-benzobicyclic skeletons is described. In this single reaction, three new bonds and two new rings can be established, highlighting the step-economics and high efficiency of this protocol.