Cyclocondensation of salicylaldehydes with alkyl acetoacetates and 2-aminobenzothiazoles or 2-amino-5-methylthiazole under classical Biginellireaction conditions gives rare hetarylamino substituted 2,2′-spirobischromanecarboxylate derivatives. The mechanism and observed stereoselectivity of the unexpected pseudo-four-component process are discussed.
Cyclocondensation of salicylaldehydes with alkyl acetoacetates and 2-aminobenzothiazoles or 2-amino-thiadiazole/thiazoles under L-proline catalysis gives 4-hetarylamino substituted chromanecarboxylate derivatives. The mechanism involving the Mannich/hemiketalization cascade reaction and the observed stereoselectivity of the three component process are discussed. (C) 2016 Elsevier Ltd. All rights reserved.