Metal-free, PTSA catalyzed facile synthesis of beta-ketoacetal from beta-chlorocinnamaldehyde

A toluene solution of beta-chlorocinnamaldehyde and dihydroxy alcohols in the catalytic presence of paratoluenesulphonic acid (PTSA) yield the beta-ketoacetal in good to outstanding amount. The catalyst (PTSA), first selectively protect the aldehydic group to form the beta-chloroacetal and the subsequent dechlorination by H2O result the beta-ketoacetal. Significant transformation was achieved with electron donating substituent attached at the para-position of cinnamaldehyde. The selective formation of beta-keto-1,3-acetal was also obtained with a mixture of 1, 2- and 1, 3- diol. The present reaction consists of a metal-free, economical, robustly feasible, sizeable functional group tolerance and high yield properties. Moreover, the use of different dihydroxy alcohols made this process more benign and valuable towards the metal-free development of ketones. First, of its kind, a rare and unusual multitasking nature of PTSA is observed. (C) 2018 Elsevier Ltd. All rights reserved.