Synthesis and Birch reduction of benzocyclopropene

Abstract

o-Bromobenzyl methyl ether reacts with nbutyl-lithium to give benzocyclopropene, Birch reduction of which gives only products related to cyclopropene ring opening.

Cycloproparenes

“…Some of the earliest recorded approaches to parent 2 and its arene homologues 6 and 126 include uses of o-bromobenzyl bromides 127 and the corresponding methyl ethers. 128,129 The ring-closing elimination sequence (path e, Scheme 1), which provides cyclobutabenzenes in almost quantitative yields, 130 has had little success in the cycloproparene series 15,[127][128][129] until recently. 131 In 1975, Saward and Vollhardt 132 reported a synthesis of rocketene 28 involving the 1,3-elimination sequence.…”

The Cycloproparenes

“…Miscellaneous Approaches. A new synthesis of cyclopropabenzene (1) involving lithiation of 55a and subsequent intramolecular cyclization was reported in 1974 by Radlick and Crawford (51). An obvious advantage of the procedure lies in its potential application to other cycloproparenes since the relevant substrates, e.g., 55b,c, are easily prepared.…”

Organometallic Derivatives of Cycloproparenes

“…The synthesis of 1 Hcyclopropabenzene (1 la) via intramolecular cyclization of 1-bromo-1-(methoxymethy1)benzene (22a) in the presence of BuLi has been reported by Radlick and Crawford some time ago [26]. At a first glance, this should be an attractive route for complexed cyclopropabenzenes.…”

“…All coordinated of H-atoms have been observed and refined. ), 45(26). HR-MS (C,SH,9C1CrSi0,): Mobs 362.018631; Mcalc 362.01969.…”