Transition-Metal-Free Cross-Coupling of Indium Organometallics with Chromene and Isochroman Acetals Mediated by BF3 center dot OEt2

A transition-metal-free coupling of triorganoindium reagents with benzopyranyl acetals mediated by a Lewis acid has been developed. The reaction of R3In with chromene and isochroman acetals in the presence of BF3 center dot OEt2 afforded 2-substituted chromenes and 1-substituted isochromans, respect...

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Bibliographic Details
Published inOrganic letters Vol. 18; no. 17; pp. 4316 - 4319
Main Authors Gil-Negrete, Jose M., Perez Sestelo, Jose, Sarandeses, Luis A.
Format Journal Article
LanguageEnglish
Published WASHINGTON Amer Chemical Soc 02.09.2016
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
ORGANIC-SYNTHESIS
TRIORGANOINDIUM REAGENTS
PROPARGYLIC ESTERS
ETHERS
ACID
ALLYLIC SUBSTITUTION-REACTIONS
ARYL HALIDES
CATALYZED ALKYNYLATION
OXOCARBENIUM IONS
ORGANOINDIUM REAGENTS
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Summary:A transition-metal-free coupling of triorganoindium reagents with benzopyranyl acetals mediated by a Lewis acid has been developed. The reaction of R3In with chromene and isochroman acetals in the presence of BF3 center dot OEt2 afforded 2-substituted chromenes and 1-substituted isochromans, respectively, in good yields. The reactions proceed with a variety of triorganoindium reagents (aryl, heteroaryl, alkynyl, alkenyl, alkyl) using only 50 mol % of the organometallic, thus demonstrating the efficiency of these species. Preliminary mechanistic studies indicate the formation of an oxocarbenium ion intermediate in the presence of the Lewis acid.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.6b02058