4-Aryl-2,3-dihydro-4H-pyrimido[2,3-b]benzothiazoles (4-Ar-DHPBs) were synthesized and their catalytic activity and selectivity in kinetic resolution of a secondary alcohol as well as in the Steglich rearrangement and related reactions were evaluated. 4-Aryl-DHPBs showed low enantioselectivity in the acylative kinetic resolution of 1-phenylethanol. Conversely, they catalyzed the Steglich rearrangement with moderate to excellent enantioselectivity, demonstrating the possibility for remote stereocontrol by introduction of a substituent at the 4-position of DHPB.

Synthesis and Catalytic Properties of 4-Aryl-2,3-dihydro-4H-pyrimido[2,3-b]benzothiazoles for Asymmetric Acyl or Carboxyl Group TransferReactions. -Some chiral dihydropyrimidobenzothiazoles are prepared by condensation of 2-aminobenzothiazoles with HCHO and styrenes and subsequent optical resolution. The derivatives (R)-and (S)-(IV) efficiently promote asymmetric acyl and carboxyl group transfer reactions of oxazole derivatives. With benzofuran and indole derivatives, however, only low or no enantioselectivity is achieved. Additionally, it is found that the catalysts do not promote kinetic resolution of secondary alcohols. -(VISWAMBHARAN, B.; OKIMURA, T.; SUZUKI, S.; OKAMOTO*, S.; J. Org. Chem. 76 (2011) 16, 6678-6685, http://dx.doi.org/10.1021/jo200984n ; Dep. Mater. Life Chem., Kanagawa Univ., Kanagawa, Yokohama 221, Japan; Eng.) -Jannicke