Dialkylborane-Catalyzed Hydroboration of Alkynes with 1,3,2-Benzodioxaborole in Tetrahydrofuran

Total Synthesis of (−)-Bafilomycin A1: Application of Diastereoselective Crotylboration and Methyl Ketone Aldol Reactions

“…Finally, treatment of the resulting alkynol with catecholborane and a catalytic amount of 9-BBN [19] produced the vinylboronic acid 4 after aqueous workup (71 % yield).…”

Biomimetic Synthesis of (+)‐Aspergillin PZ

“…[20] Following TMS-deprotection, the crude solution of free enyne was subjected to Cy 2 BH-accelerated hydroboration using catecholborane to furnish catechol ester 17 , which was additionally used without purification. [21] Dienophile precursor 19 was readily prepared from lactam 18 by C -carbomethoxylation and selenation in excellent yield. [22] Treatment of selenide 19 with H 2 O 2 then provided 14 , which was used immediately in Diels-Alder studies.…”

Biomimetic Synthesis of (+)‐Aspergillin PZ

“…Among the propargyl anions and derivatives of epoxide 22 explored to establish the 1,2-anti diol of 2,o rganometallic addition by this method onto this unprotected epoxy alcohol was the only reproducible and scalable combination. [21] Dienophile precursor 19 was readily prepared from lactam 18 by C-carbomethoxylation and selenation in excellent yield. [17] Unfortunately,extensive efforts to achieve this transformation by the method of Negishi (ZrCp 2 Cl 2 /AlMe 3 ) proved to be highly substrate dependent and was found to work solely on free diol 23 and only in moderate yields (< 60 %).…”

“…[20] Following TMS-deprotection, the crude solution of free enyne was subjected to Cy 2 BHaccelerated hydroboration using catecholborane to furnish catechol ester 17,w hich was additionally used without purification. [21] Dienophile precursor 19 was readily prepared from lactam 18 by C-carbomethoxylation and selenation in excellent yield. [22] Tr eatment of selenide 19 with H 2 O 2 then provided 14,w hich was used immediately in Diels-Alder studies.…”