Zinc Catalyzed and Mediated Propargylations with Propargyl Boronates
摘要:
The utility of allenyl and propargyl boronates for the propargylation of aldehydes and ketones mediated by zinc is presented. The reaction Is catalytic in zinc with allenyl or propargyl borolanes. The propargylation with crystalline and air-stable propargyl diethanolamine boronates was also achieved. A catalytic cycle is proposed, and preliminary mechanistic studies are discussed.
Regioselective Addition Reactions of Propargyl Bromides to Carbonyl Compounds with Gallium Catalyzed by Indium
作者:Phil Ho Lee、Hyun Kim、Kooyeon Lee
DOI:10.1002/adsc.200505046
日期:2005.7
propargyl bromides having substituents at the γ-position and gallium in the presence of 5 mol % of indium with aldehydes and ketones selectively produced homoallenyl alcohols in good to excellent yields. Treatment of organogallium reagents obtained from propargyl bromide or propargyl bromides having substituents at the α-position and gallium in the presence of 5 mol % of indium with carbonyl compounds selectively
CpTiCl<sub>2</sub>
, an Improved Titanocene(III) Catalyst in Organic Synthesis
作者:Esther Roldan-Molina、Natalia M. Padial、Luis Lezama、J. Enrique Oltra
DOI:10.1002/ejoc.201801120
日期:2018.11.25
CpTiCl2, an improved titanocene(III) single‐electron transfer catalyst, under mild conditions provides excellent yields of homoallylic and homopropargylic alcohols in Barbier‐type allylation and propargylation reactions. Moreover, in the presence of a BOX ligand, it was capable of catalyzingenantioselective intramolecular allylations and propargylations (cyclizations) of ketones.
Asymmetric Propargylation of Ketones Using Allenylboronates Catalyzed by Chiral Biphenols
作者:David S. Barnett、Scott E. Schaus
DOI:10.1021/ol201535b
日期:2011.8.5
Chiralbiphenolscatalyze the enantioselective asymmetric propargylation of ketones using allenylboronates. The reaction uses 10 mol % of 3,3′-Br2-BINOL as the catalyst and allenyldioxoborolane as the nucleophile, in the absence of solvent, and under microwave irradiation to afford the homopropargylic alcohol. The reaction products are obtained in good yields (60–98%) and high enantiomeric ratios (3:1–99:1)
Reductive addition of propargylic acetates to carbonyl compounds proceeded smoothly at room temperature by using SmI2 and a catalytic amount of Pd(PPh3)4 to give the corresponding acetylenic and/or allenic alcohols with appreciable selectivity. The method is useful especially for the preparation of tri- and tetrasubstituted allenic alcohols.
Ring Opening/Fragmentation of Dihydropyrones for the Synthesis of Homopropargyl Alcohols
作者:Jumreang Tummatorn、Gregory B. Dudley
DOI:10.1021/ja801018r
日期:2008.4.1
Ring-opening/C-C bond cleavage reactions induced by nucleophilic addition of methyl Grignard to 5,6-dihydro-2-pyrone (DHP) triflates 1 furnish homopropargyl alcohols (1 --> 2) stereospecifically with respect to the stereochemistry of 1. Carbonyl extrusion from DHP triflates provides a unified and operationally simple strategy for preparing chiral homopropargyl alcohols.