Preparation of Organoaluminum Reagents from Propargylic Bromides and Aluminum Activated by PbCl2 and Their Regio- and Diastereoselective Addition to Carbonyl Derivatives
作者:Li-Na Guo、Hongjun Gao、Peter Mayer、Paul Knochel
DOI:10.1002/chem.201000523
日期:2010.8.23
propargylic and allenic aluminum reagents have been easily prepared by a direct insertion of aluminum into propargylic bromides in the presence of PbCl2 (1 mol %). These organoaluminum reagents react with carbonyl compounds to afford the corresponding allenic alcohols or homopropargylic alcohols in good to excellent yields with high regio‐ and diastereoselectivity.
Pyridinium triflate catalyzed intramolecular alkyne-carbonyl metathesis reaction of O-propargylated 2-hydroxyarylaldehydes
作者:Manoj Kumar Saini、Harshita Singh Korawat、Shashi Kant Verma、Ashok K. Basak
DOI:10.1016/j.tetlet.2020.152657
日期:2020.12
3,5-Dibromopridinium trifluoromethanesulfonate catalyzes the intramolecular alkyne-carbonyl metathesis reaction of a variety of O-propargylated 2-hydroxyarylaldehydes and ketonesbearingalkyl, aryl and heteroaryl substituted internal alkynes to provide various 3-(hetero)aroyl 2H-chromenes in high yields.
Borylative Cyclization of 1,6-Allenynes Driven by BCl<sub>3</sub>
作者:Chun-Hua Yang、Xiangkun Sun、Congcong Niu、Zhiwei Zhang、Mingzhu Liu、Fangjie Zheng、Ling Jiang、Xiangtao Kong、Zhantao Yang
DOI:10.1021/acs.orglett.1c03062
日期:2021.10.15
A metal-free intramolecular borylative cyclization of 1,6-allenynes driven by BCl3 was developed. This method provides a general and practical strategy to construct valuable pyrrolidines containing all-carbon quaternary centers or 3,5-dihydroazepine derivatives depending on the substituents of the allene, with conjugative and sterically hindered phenyl groups favoring the latter.
Gold(I)-Catalyzed Enantioselective Ring Expansion of Allenylcyclopropanols
作者:Florian Kleinbeck、F. Dean Toste
DOI:10.1021/ja904055z
日期:2009.7.8
The asymmetric gold(I)-catalyzedring expansion of 1-allenylcyclopropanols is described. The method provides synthetically valuable cyclobutanones with a vinyl-substituted quaternary stereogenic center in high enantioselectivities and yields. The method shows a broad substrate scope, tolerating protected alcohols and amines, alkenes, unsaturated esters, and acetals. The reaction is easily adjustable
Visible light initiates the stereoselective formation of two new bonds, a CC and a CSi bond, during the addition of acylsilanes to alkynes. At room temperature this photochemicallyinduced transformation can be applied for the preparation of chromone derivatives in a highly atom-economic manner.