Synfacts 2021; 17(04): 0427
DOI: 10.1055/s-0040-1706718
Metals in Synthesis

Directed ortho-Lithiation of Benzamides

Contributor(s):
Paul Knochel
,
Andreas Hess
de Silva SO, Reed JN, Snieckus V. * University of Waterloo, Canada
Directed Lithiation of N,N-Diethylbenzamides. Regiospecific Synthesis of Contiguously Tri- and Tetra-Substituted Alkoxybenzenes.

Tetrahedron Lett. 1978;
51: 5099-5102
DOI: 10.1016/S0040-4039(01)85822-6
 

Significance

Snieckus and co-workers reported a regiospecific ortho-lithiation of various N,N-diethylbenzamides using sec-BuLi and TMEDA in THF. The formed lithiated species were trapped with a range of electrophiles and the desired products were obtained in moderate to excellent yield.


Comment

The authors demonstrated the utility of this methodology for the synthesis of naturally occurring alkaloids. Thus, a formylated product was converted by successive reduction and cyclization into meconine in 90% yield. Subsequent hydrolysis furnished opianic acid in 50% yield.




Publication History

Article published online:
18 March 2021

© 2021. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany