Optical Resolution of (±)‐2,3‐Dihydro‐2‐phenyl‐4H‐1‐benzothiopyran‐4‐one

Abstract

Optical resolution of the title compound was achieved wing the opticaUy active reagent ( 9 tS+phenetbyl)mniomazide (2).

Resolution and configurational assignment of 3,4,5,6-tetrahydro-2-methyl-2,6-methano-2H-1-benzoxocine derivatives

“…9 Its chemical resolution was carried out with (ϩ)-(1-phenylethyloxamoyl)hydrazine 7, a carbonyl derivatizing agent 10-13 (Scheme 1). In contrast to previous findings, [10][11][12][13] where the resolution of chiral ketone derivatives with 7 resulted in the two corresponding diastereomers, which could be separated by fractional crystallization, the condensation of rac-6 with this reagent, monitored by TLC, showed the formation of four products of comparable ratio instead of two. The 1 H NMR spectrum of the crude product clearly indicated that the syn Z-and anti E-isomers of both diastereomers [(Z )-(ϩ)-8/(E )-(ϩ)-8, (Z )-(Ϫ)-8/(E )-(Ϫ) -8] were present in this mixture (Scheme 1).…”