Salicylaldehyde → 1-(4,5-Dihydro-2-thiazolyl)-1,3-dihydro-3-[(2-hydroxyphenyl)methylene]-2H-indol-2-one

Participants

Reaction Steps

To a warmed solution of 1-(2-thiazolin-2-yl)-indolin-2-one (prepared as described in Example 3A; 2.0 g; 9.2 mmole) and salicylaldehyde (1.6 g; 12.9 mmole) in dry benzene (100 ml) is added a small amount of piperidine (0.6 ml). The resultant mixture is heated at reflux temperature for 2 hours. The reaction mixture is extracted with dilute HCl solution (5 ml of concentrated HCl in 120 ml of water) twice. The acidic layers are combined and treated with saturated NaHCO3 solution until pH paper indicates it is slightly basic. The precipitate is collected by filtration and washed well with water. This crude material is recrystallized from acetone/hexane (treated with charcoal) to give 1.9 g of the product: m.p. 195.5°-197° C.

Provenance & Evidence