Rhodium-mediated enantioselective cyclopropanation of allenes.
Reaction of monosubstituted allenes with aryldiazoacetate esters under dirhodium tetracarboxylate catalysis led to alkylidene cyclopropane products in 80-90% ee. Monosubstituted alkyl- and arylallene substrates gave 60-75% yield under standard conditions, while yields for 1,1-disubstituted allenes were significantly lower. Cyclopropanation of 1-methyl-1-(trimethylsilyl)allene proceeded in higher yield than other 1,1-disubstituted substrates, suggesting rate enhancement mediated by a significant beta-silicon effect.
Gregg
Timothy M
TM
Department of Chemistry and Biochemistry, Canisius College, Buffalo, New York 14208, USA. greggt@canisius.edu
Farrugia
Mark K
MK
Frost
John R
JR
D000466:Alkadienes / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D000466:Alkadienes; D003521:Cyclopropanes; D012238:Rhodium