Straightforward and direct access to β-seleno- amines and sulfonylamides via the controlled addition of phenylselenomethyllithium (LiCH2SePh) to imines

The Versatility of the Roskamp Homologation in Synthesis

Modern organic synthesis continues to benefit from the flexibility of α-diazo carbonyl intermediates. In the context of homologation processes, the Roskamp reaction-first introduced in 1989-has become a valuable tool due to its selectivity and mild condition reactions for accessing important synthons amenable to further functionalization as β-keto esters. The fine-tuning of reaction parameters-including the nature of Lewis acids, solvents, and temperature-has enabled the development of catalyzed continuous-flow methodologies, as well as a series of asymmetric variants characterized by high transformation rates, excellent stereocontrol, and formidable chemoselectivity. This review aims to emphasize the attractive features of the Roskamp reaction and its applicability for addressing challenging homologation processes.

Direct and straightforward transfer of C1 functionalized synthons to phosphorous electrophiles for accessing gem-P-containing methanes

The direct transfer of different α-substituted methyllithium reagents to chlorinated phosphorous electrophiles of diverse oxidation state (phosphates, phosphine oxides and phosphines) is proposed as an effective strategy to synthesize geminal P-containing methanes. The methodology relies on the efficient nucleophilic substitution conducted on the P-chlorine linkage. Uniformly high yields are observed regardless the specific nature of the carbanion employed: once established the conditions for generating the competent nucleophile (LiCH₂Hal, LiCHHal₂, LiCH₂CN, LiCH₂SeR etc.) the homologated compounds are obtained via a single operation. Some P-containing formal carbanions have been evaluated in transferring processes, including the carbonyl-difluoromethylation of the opioid agent Hydrocodone.