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Chemo‐ and Regioselective Intermolecular Cyclotrimerization of Terminal Alkynes Catalyzed by Cationic Rhodium( I )/Modified BINAP Complexes: Application to One‐Step Synthesis of Paracyclophanes
Author(s) -
Tanaka Ken,
Toyoda Kazuki,
Wada Azusa,
Shirasaka Kaori,
Hirano Masao
Publication year - 2005
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.200401017
Subject(s) - regioselectivity , alkyne , rhodium , cationic polymerization , chemistry , intermolecular force , catalysis , combinatorial chemistry , medicinal chemistry , polymer chemistry , organic chemistry , molecule
A highly regioselective intermolecular cyclotrimerization of terminal alkynes has been developed based on the use of the cationic rhodium( I )/DTBM‐Segphos complex. This method can be applied to a variety of terminal alkynes to provide 1,2,4‐trisubstituted benzenes in high yield and with high regioselectivity. A chemo‐ and regioselective intermolecular crossed‐cyclotrimerization of dialkyl acetylenedicarboxylates with a variety of terminal alkynes has also been developed based on the use of the cationic rhodium( I )/H8‐BINAP complex, furnishing 3,6‐disubstituted phthalates in high yields. It constitutes a highly efficient new method for intermolecular crossed‐cyclotrimerization of two different monoynes in terms of catalytic activity, chemo‐ and regioselectivity, scope of substrates, and ease of operation. The versatility of this new crossed‐alkyne cyclotrimerization procedure is demonstrated through its application to one‐step synthesis of a [6]metacyclophane and [7]–[12]paracyclophanes from the corresponding terminal α,ω‐diynes. Mechanistic studies have revealed that the chemo‐ and regioselectivity of this crossed‐alkyne cyclotrimerization are determined by the preferential formation of a specific rhodium metallacycle derived from a terminal alkyne and a dialkyl acetylenedicarboxylate.