Di- and Trisubstituted γ-Lactams via Rh(II)-carbenoid Reaction of N-Cα-Branched, N-Bis(trimethylsilyl)methyl α-Diazoamides. Synthesis of (±)-α-Allokainic Acid

K2S2O8-Mediated Radical Cyclization of 1,6-Enyne for the Synthesis of Diiodonated γ-Lactams

A novel and convenient K₂S₂O₈-mediated diiodo cyclization of 1,6-enynes for the facile synthesis of functionalized γ-lactam derivatives has been developed. This reaction features mild and transition-metal-free conditions, which offer a green and efficient entry to synthetically important γ-lactam scaffolds. Mechanistic studies suggest that iodide radicals initiate the cascade cyclic transformation.

A Pd-catalyzed one-pot cascade consisting of C-C/C-O/N-N bond formation to access benzoxazine fused 1,2,3-triazoles

A Pd-catalyzed one-pot cascade consisting of C-C/C-O/N-N bond formation to access clinically important fused 1,2,3-triazoles using N-aryl-α-(tosylhydrazone)acetamides with isocyanide has been developed. Besides, various substitutions on the N-aryl part of acetamides along with different isocyanides show good compatibility in this protocol. Next, two plausible mechanistic routes were proposed; however, one of the routes was more favourable which involved the formation of a benzoxazine ring first followed by the realization of a triazole ring. Additionally, the more favourable mechanistic route was investigated using DFT studies which suggests that the formations of a Pd(II)-isocyanide complex and α-diazoimino intermediates were key steps in the catalytic cycle.

Visible light-induced aerobic oxidative cross-coupling of glycine esters with α-angelicalactone: a facile pathway to γ-lactams

A rapid synthesis of substituted γ-lactams is achieved via metal-free photocatalyzed aerobic oxidative dehydrogenative formal [2 + 3] cyclization of glycine esters with α-angelicalactone.

Recent progress towards transition metal-catalyzed synthesis of γ-lactams

The scope of transition metal-catalyzed synthesis of functionalized γ-lactams has broadened tremendously in the last decade (see the picture). These metal-catalyzed processes are reviewed by highlighting their specificity and applicability, and the mechanistic rationale is presented where possible.