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Iron‐Catalyzed Diboration and Carboboration of Alkynes
Author(s) -
Nakagawa Naohisa,
Hatakeyama Takuji,
Nakamura Masaharu
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406595
Subject(s) - alkyne , chemistry , alkyl , halide , catalysis , stereoselectivity , trapping , triple bond , medicinal chemistry , boron , combinatorial chemistry , polymer chemistry , organic chemistry , double bond , ecology , biology
Abstract An iron‐catalyzed diboration reaction of alkynes with bis(pinacolato)diboron (B 2 pin 2 ) and external borating agents (MeOB(OR) 2 ) affords diverse symmetrical or unsymmetrical cis ‐1,2‐diborylalkenes. The simple protocol for the diboration reaction can be extended to the iron‐catalyzed carboboration of alkynes with primary and, unprecedentedly, secondary alkyl halides, affording various tetrasubstituted monoborylalkenes in a highly stereoselective manner. DFT calculations indicate that a boryliron intermediate adds across the triple bond of an alkyne to afford an alkenyliron intermediate, which can react with the external trapping agents, borates and alkyl halides. In situ trapping experiments support the intermediacy of the alkenyl iron species using radical probe stubstrates.