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Stereoselectivity in Metal Carbene Addition to a Carbon‐Carbon Triple Bond Tied to the Reactant Diazoacetate Through a Chiral Linker
Author(s) -
Doyle Michael P.,
Weathers Thomas M.,
Wang Yuanhua
Publication year - 2006
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200600349
Subject(s) - chemistry , carbene , triple bond , diastereomer , propargyl , stereoselectivity , diazo , catalysis , intramolecular force , medicinal chemistry , carbon fibers , isomerization , ethyl diazoacetate , stereochemistry , double bond , organic chemistry , cyclopropanation , materials science , composite number , composite material
The trajectory of a carbon‐carbon triple bond onto a metal carbene for cyclopropene formation is opposite to that of a carbon‐carbon double bond in the same system. Diazoacetates prepared from the butane‐2,3‐diacetals (BDA) of ( L )‐ and ( D )‐threitol were employed to examine diastereoselectivity in cyclopropenation. The absolute configuration of the predominant isomer was opposite in intramolecular metal carbene additions to propargyl and allyl substituents. Diastereoselectivities in the dirhodium( II ) carboxamidate‐catalyzed diazo decomposition reactions are as high as 99:1 with match/mismatch selectivites for substrate and catalyst, dependent on catalyst configuration, and are favored in the order: Rh 2 (MEPY) 4 >Rh 2 (MEOX) 4 >Rh 2 (MEAZ) 4 > Rh 2 (MPPIM) 4 . The reactions catalyzed by the Cu(CH 3 CN) 4 PF 6 /PhBox system produce the same set of diastereoisomers in a complimentary match/mismatch selectivity that also reaches 99:1.