Highly diastereoselective formal nucleophilic substitution of bromocyclopropanes.
A highly diastereoselective formal nucleophilic substitution of bromocyclopropanes with oxygen- and nitrogen-based nucleophiles was demonstrated. The reaction proceeds via a base-assisted dehydrohalogenation producing a cyclopropene intermediate, which subsequently undergoes addition of a pronucleophile across the strained double bond. Very high chemoselectivity toward addition of primary and secondary alkoxides, as well as N-nucleophiles, in the presence of tert-butoxide base was observed, whereas phenoxides did not undergo addition under these reaction conditions. Facial selectivity of the addition can be efficiently controlled either by sterics or through a directing effect of an amide, carboxylate, and an o-aminomethylphenol function. Employment of tethered optically active amino alcohols as pronucleophiles allowed for efficient assembly of homochiral bicyclic compounds.
Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045-75832, USA.
Bassam K
BK
Alnasleh
William M
WM
Sherrill
Marina
M
Rubina
Joseph
J
Banning
Michael
M
Rubin