Formation of a chiral β-lactam by photocyclisation of an achiral oxo amide in its chiral crystalline state

Abstract

Chiral crystals of the achiral 0x0 amide N,N-di-isopropylphenylglyoxylamide, prepared in large quantities, were irradiated in the solid state to give the optically active B-lactam 3-hydroxy-1 -isopropyl-4,4-dimethyl-3-phenylazetidin-2-one in high optical and chemical yields.

Absolute asymmetrische Synthese: Ursprung, Beeinflussung und Verstärkung von Chiralität

“…[109] Über einen bemerkenswerten Fall ± die Photocyclisierung des Diisopropylamids 22 ± berichteten Toda et al (Schema 10). [110] Wegen der Verdrillung um eine C(O)-C(O)-Bindung liegt im chiralen Kristall eine helicale Struktur vor, Schema 10. Bildung des chiralen b-Lactams 23 durch Photocyclisierung von 22 im Kristall.…”

Absolute Asymmetric Synthesis: The Origin, Control, and Amplification of Chirality

“…[109] A remarkable caseÐthe photocyclization of the diisopropyl amide 22Ðwas reported by Toda et al (Scheme 10). [110] A helical conformation is found in the chiral crystal as a consequence of a twisting around the CO À CO bond, and this conformation is locked by photocyclization to afford b-lactam 23 with 93 % ee. A prominent Scheme 10.…”

“…Formation of chiral b-lactam 23 by photocyclization of 22 in the crystal. [110] REVIEWS [22]-photocyclization of one enantiomorphous form of achiral a,b-unsaturated thioamide 24 via diradical 25 using the chiral crystal environment (Scheme 11). [111] Scheme 11.…”

Asymmetric Photochemistry and Photochirogenesis

“…[14] A further example is the photochemical synthesis of a b-lactam from an achiral N,N-dialkylarylglyoxylamide, [15] a substrate which has also been used frequently in the chiral crystal methodology. [16] …”