Mild-Condition Synthesis of Allenes from Alkynes and Aldehydes Mediated by Tetrahydroisoquinoline (THIQ)
摘要:
A practical 1,2,3,4-tetrahydroisoquinoline (THIQ)-mediated synthesis of 1,3-disubstituted allenes from terminal alkynes and aldehydes under mild conditions in the presence of CuBr first and then ZnI2 was reported. This telescoped allene synthesis reaction includes three consecutive steps and two reactions: first, a room-temperature CuBr-catalyzed synthesis of propargylamines, exo-yne-THIQs, from terminal alkynes, aldehydes, and THIQ then filtration of the CuBr catalyst, and finally the ZnI2-mediated allene synthesis from the generated exo-yne-THIQs under mild conditions (either at room temperature or heating at 50 or 75 degrees C). A wide range of aliphatic or aromatic aldehydes and terminal alkynes are tolerated, affording the allene products in up to 92% yield. Especially, temperature-sensitive aldehydes can be used in the reaction system. Preliminary exploration of the asymmetric allene synthesis has also been conducted, and a moderate enantioselectivity has been achieved. Finally, the relative reactivities of several secondary amines were compared with THIQ, showing that THIQ is the best of these amines in the synthesis of allenes under mild reaction conditions.
Ligand‐Controlled Regiodivergent Cyanoboration of Internal Allenes by Copper Catalysis
作者:Hui Hu、Guo‐Cui Ji、Linjuan Jiang、Siwei Bi、Yuan‐Ye Jiang、Yuanhong Liu
DOI:10.1002/anie.202210338
日期:2022.12.19
The first copper-catalyzed regiodivergent cyanoboration of internal allenes with B2pin2 and NCTS derivatives has been developed. MeOH was identified as the necessary additive for the regeneration of LCu-Bpin species. Computational studies revealed that the copper-mediated allylic cyanation is the regio- and stereo-determining step, while the MeOH-assisted transmetalation with B2pin2 is the rate-determining
已经开发出第一个铜催化的具有 B 2引脚2和 NCTS 衍生物的内部丙二烯区域发散氰基硼化反应。MeOH 被确定为 LCu-Bpin 物种再生的必要添加剂。计算研究表明,铜介导的烯丙基氰化作用是区域和立体决定步骤,而甲醇辅助的 B 2 pin 2金属转移是速率决定步骤。