Yield:-

Reaction Conditions:

in benzene; for 7 h;Reflux;

Steps:

A 1 L round bottom flask, outfitted with Dean-Stark adapter, a reflux condenser, and a PTFE-coated stirbar, was charged with 3-bromobenzaldehyde (50.0 g, 270 mmol, 1 equiv), aminoacetaldehyde dimethyl acetal (28.42 g, 1 equiv) and benzene (270 mL). The resulting solution became cloudy within 2 minutes and was heated at reflux until approximately 5 mL of water is collected in the Dean-Stark adapter (~7 hours). The solvent was then evaporated to afford the w-bromobenzalaminoacetal as a light yellow viscous liquid (~75 g) which was directly used in the subsequent cyclization step.

References:

WO2010/123545,2010,A2 Location in patent:Page/Page column 67-68