Gilman-Speeter condensation
The Gilman-Speeter condensation is a name reaction from the field of organic chemistry , which was first published in 1943 by the American chemists Henry Gilman (1893–1986) and Merrill E. Speeter . It is an efficient synthesis of a β - lactam from a Reformatsky reagent and an imine .
Overview
The halide- substituted , in this case bromide-substituted , Reformatsky reagent is reacted with an imine , here N -methylmethanimine, to form a β- lactam, in this case 1-methyl azetidin- 2-one:
With the Gilman-Speeter condensation , 3-alkyl-4-alkenyl-substituted β- lactams can also be synthesized through the use of appropriate imines .
Reaction mechanism
A suggestion for the reaction mechanism:
The ( Reformatsky reagent ) 2 is synthesized from the α-bromo ester 1 by adding a zinc atom . Then the zinc organyl 2 is added to the C = N double bond of the imine . The intermediate 3 cyclizes to the heterocycle 4 which reacts further to the β - lactam 5 . The radicals have the following meanings: R 1 = alkyl radical ; R 2 = H or alkyl radical; R 3 = alkyl or aryl radical ; R 4 = H, alkyl or aryl radical.
Individual evidence
- ^ Henry Gilman, Merrill Speeter: The Reformatsky Reaction with Benzalaniline . In: Journal of the American Chemical Society . tape 65 , no. 11 , 1943, pp. 2255-2256 , doi : 10.1021 / ja01251a503 .
- ↑ Plato A. Magriotis: Recent Progress in the Enantioselective Synthesis of β-lactam: Development of the First Catalytic Approaches . In: Angewandte Chemie International Edition . tape 40 , no. 23 , 2001, p. 4377-4379 , doi : 10.1002 / 1521-3773 (20011203) 40:23 <4377 :: AID-ANIE4377> 3.0.CO; 2-J .
- ^ A b Z. Wang (ed.): Comprehensive Organic Name Reactions and Reagents, 3 Volume Set , John Wiley & Sons, Hoboken, New Jersey, 2009, ISBN 978-0-471-70450-8 , p. 1235.