Asymmetric ruthenium-catalysed [2+2] cycloadditions between bicyclic alkenes and chiral aryl-substituted acetylenic acyl camphorsultam alkynes.
The regio- and absolute stereochemistry of (7S)-N-[4-(3-thienyl)tricyclo[4.2.1.0(2,5)]non-3-en-3-ylcarbonyl]-2,10-camphorsultam tetrahydrofuran hemisolvate, C(24)H(29)NO(3)S(2).0.5C(4)H(8)O, and (7S)-N-[4-(4-tolyl)tricyclo[4.2.1.0(2,5)]non-3-en-3-ylcarbonyl]-2,10-camphorsultam, C(27)H(33)NO(3)S, have been established. One contains a half-occupancy tetrahydrofuran solvent molecule located on a twofold axis and the other contains two crystallographically unique molecules which are nearly identical. The extended structures of both complexes can be explained via weak C-H...O interactions, which link the molecules together into two-dimensional sheets in the ab plane for the thienyl complex and ultimately into a three-dimensional structure for the tolyl derivative. The stereochemistry of both structures confirms that [2+2] cycloadditions of bicyclic alkenes and alkynes catalysed by ruthenium are exclusively exo.
Goodreid
Jordan D
JD
Department of Chemistry, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1.
Jennings
Michael C
MC
Tam
William
W