BASE CYCLIZATION OF VINYLIC CYSTEINE SULFONES

Vinylic cysteine sulfones (1a, b, c) cyclize in dilute base under mild conditions to cyclic sulfone amino acids. In each case, two isomers (2 and 3) are produced. Nmr analysis shows that these differ in configuration at atom 5 and in ring conformation. The less soluble isomer (2) has the R configuration at 5 and a conformation with the carboxyl axial. The more soluble isomer (3) has the S configuration at 5, and a ring conformation with the carboxyl equatorial. © 1968, American Chemical Society. All rights reserved.