Synthesis of rhenabenzenes from the reactions of rhenacyclobutadienes with ethoxyethyne

Ran Lin; Ka-Ho Lee; Ka Chun Poon; Herman H Y Sung; Ian D Williams; Zhenyang Lin; Guochen Jia

doi:10.1002/chem.201403186

Synthesis of rhenabenzenes from the reactions of rhenacyclobutadienes with ethoxyethyne

Chemistry. 2014 Nov 3;20(45):14885-99. doi: 10.1002/chem.201403186. Epub 2014 Sep 12.

Authors

Ran Lin¹, Ka-Ho Lee, Ka Chun Poon, Herman H Y Sung, Ian D Williams, Zhenyang Lin, Guochen Jia

Affiliation

¹ Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong), Fax: (+852) 2358-1594.

PMID: 25220667
DOI: 10.1002/chem.201403186

Abstract

Treatment of Na[Re(CO)5 ] with RCCCO2 Et (R=phenyl, naphthalen-1-yl, phenanthren-9-yl and pyren-1-yl) followed by reaction with acetyl chloride and ethanol afforded the rhenacyclobutadienes Re{-C(R)C(CO2 Et)C(OEt)}(CO)4 . Reactions of these rhenacyclobutadienes with HCCOEt produced rhenabenzenes Re{-C(R)C(CO2 Et)C(OEt)CHC(OEt)}(CO)4 . Except for R=Ph, new rhenacyclobutadienes with pendant alkenyl substituents Re{-C(R)C(C(OEt)CH(CO2 Et))C(OEt)}(CO)4 were also isolated from these reactions. The NMR spectroscopic and X-ray structural data, as well as the aromatic stabilization energy (ASE) values suggest that the rhenabenzenes are aromatic, with extensive delocalized π character.

Keywords: aromaticity; metallabenzene; metallacycles; rhenium; structure elucidation.