Reactions of transition metal compounds with macrocyclic alkadiynes : IV*. Intramolecular transannular cyclizations with cyclopentadienyldicarbonylrhodium

Abstract

The macrocyclic alkadiynes, 1,7-cyclododecadiyne, 1,7-cyclotridecadiyne, 1,7- and 1,8-cyclotetradecadiyne, and 1,8-cyclopentadecadiyne react with C 5H 5Rh(CO) 2 in boiling cyclooctane to give pale yellow to white volatile compounds of the compositon C 5H 5Rh(alkadiyne) in which the macrocyclic alkadiyne has undergone an intramolecular transannular cyclization to form a tricyclic cyclobutadiene derivative. The reaction of 1,7-cyclododecadiyne with C 5H 5Rh(CO) 2 also gives a dimer of 1,7-cyclododecadiyne containing a benzene ring. Corresponding reactions of the simple alkynes RCCR (R = C 2H 5 and C 6H 5) with C 5H 5Rh(CO) 2 in boiling cyclooctane failed to give any rhodium—cyclobutadiene derivatives. Instead the reaction of 3-hexyne with C 5H 5Rh(CO) 2 under these conditions gave orange-red (C 5H 5) 2Rh 2(CO)C 4(C 2H 5) 4 and purple-black (C 5H 5) 3Rh 3(CO)(C 2H 5CCC 2H 5) and the reaction of diphenylacetylene with C 5H 5Rh(CO) 2 gave a low yield of the orange complex (C 5H 5) 3Rh 3(C 6H 5CCC 6H 5). The infrared, 1H NMR, and mass spectra of these new cyclopentadienylrhodium complexes are described.