Reactions of (1‐nitroethenyl)sulfonylbenzene,a nitroethene derivative geminally substituted by a second W‐group

Nitroaldol reaction of phenylsulfonylnitromethane with formaldehyde affords a mixture of 2,4‐dinitro‐2,4‐bis(phenylsulfonyl)butan‐1‐ol and 2,4‐dinitro‐2,4‐ bis(phenylsulfonyl)pentane‐1,5‐diol. Treatment of this mixture with base followed by reacidification affords 1,1'‐(1,3‐dinitro‐1,3‐propanediyl)bis(sulfonyl)]bis(benzene) as a mixture of (R*, R*) and (R*, S*)‐diastereomers from which the (R*, S*)‐diastereomer can be obtained pure. The intermediate in the nitroaldol reaction is (1‐nitroethenyl)sulfonylbenzene and, if dienes are present, additional products are also obtained. If either (E)‐2‐methyl‐1,3‐pentadiene or 1‐(1‐methylethenyl)cyclohexene are present, typical Diels‐Alder adducts are obtained with the major isomers explainable by assuming a transition state in which the nitro group is endo. If furan is present, its formal conjugate addition product, 2‐2‐nitro‐2‐(phenylsulfonyl)ethyl]furan, is formed. If cyclooctatetraene is present, it first dimerizes and then affords isomeric Diels‐Alder cycloadducts of the dimer. Semiempirical calculations comparing the LUMO energies of (1‐nitroethenyl)sulfonylbenzene to the corresponding trans‐1,2 isomer are presented to explain relative reactivity of 1,1‐ and 1,2‐disubstituted dienophiles. Copyright © 2009 John Wiley & Sons, Ltd.