Aromatic alkenylation using electrophilic organogallium reagent generated from allenylsilane and GaCl3
摘要:
Aromatic hydrocarbons are alkenylated with silylallene in the presence of GaCl3 at -90 degreesC. Organometallic electrophiles generated from the allene and GaCl3 are the active species in this reaction. A modest level of ortho-selectivity is observed. While the silylallene reacts exclusively at the 2-position, 1,2-alkradiene reacts at the 1-position predominantly. (C) 2001 Elsevier Science Ltd. All rights reserved.
Regioselective Allene Synthesis and Propargylations with Propargyl Diethanolamine Boronates
摘要:
The utility of propargyl diethanolamine boronates as reagents for the preparation of allenes and homopropargylic alcohols is presented. Protonolysis with TFA and electrophilic substitution with N-halosuccinimides proceeded with inversion to provide the corresponding allene in high yield and regioselectivity. Alternatively, the propargylation of aldehydes was achieved with use of the in situ generated lithiated complex.
Palladium-catalyzed Cycloaddition of Alkynyl Aryl Ethers to Allenes to Form a 2,3-Bismethylidene-2,3-dihydro-4<i>H</i>-1-benzopyran Framework
作者:Yasunori Minami、Mayuko Kanda、Tamejiro Hiyama
DOI:10.1246/cl.130894
日期:2014.2.5
Palladium-catalyzed cycloaddition of alkynyl aryl ethers to allenes proceeds through o-C–H activation to give 2,3-dihydro-4H-1-benzopyran derivatives containing 2,3-exo-double bonds. These benzopyr...
The catalyticCHaddition of pyridines to allenes has been achieved for the first time by using a half‐sandwich scandium catalyst, thus constituting a straightforward and atom‐economical route for the synthesis of alkenylated pyridine derivatives. The reaction proceeded regio‐ and stereoselectively, affording a new family of alkenylated pyridine compounds which are otherwise difficult to synthesize
A CuH-catalyzed enantioselective and regiodivergent allyl addition to ketones with allenylsilanes has been developed. Various tertiary homoallylic alcohols bearing an alkenyl silane or an allyl silane group were synthesized with high regioselectivities and excellent enantioselectivities.
Aromatic hydrocarbons are alkenylated with silylallene in the presence of GaCl3 at -90 degreesC. Organometallic electrophiles generated from the allene and GaCl3 are the active species in this reaction. A modest level of ortho-selectivity is observed. While the silylallene reacts exclusively at the 2-position, 1,2-alkradiene reacts at the 1-position predominantly. (C) 2001 Elsevier Science Ltd. All rights reserved.