"On Water" Organocatalyzed [4 + 2] Cycloaddition of Enones and Nitro Dienes for the Enantioselective Synthesis of Densely Substituted Cyclohexanones.
An "on water" hydroquinine-based primary amine-benzoic acid organocatalyst system was found to be best suited to produce 3,4,5-trisubstituted cyclohexanones with a nitro group in the 4-position from enones and nitro dienes under ambient conditions in good yield, with good diastereoselectivity, and with excellent enantioselectivity. An appreciable rate enhancement by water was observed compared to organic solvents. Mechanistic analysis of the reaction suggests that it followed an endo [4 + 2] cycloaddition with enamine of enone as diene and nitro diene as dienophile.
Bio-Organic Division, Bhabha Atomic Research Centre , Trombay, Mumbai 40008, India.
Ganga B
GB
Vamisetti
Bio-Organic Division, Bhabha Atomic Research Centre , Trombay, Mumbai 40008, India.
Raghunath
R
Chowdhury
Solid State Physics Division, Bhabha Atomic Research Centre , Trombay, Mumbai 400085, India.
Mukesh
M
Kumar
Bio-Organic Division, Bhabha Atomic Research Centre , Trombay, Mumbai 40008, India.
Sunil K
SK
Ghosh