Inhibition of Kornblum Reaction with Lithium Salts in S2 Reactions of Sulfonates and a Nucleophile Containing a Pyridine -Oxide Moiety: Convergent and Selective Synthesis of an MRGPRX2 Antagonist.

A critical step in the development of a convergent synthesis of an MRGPRX2 antagonist () was the S2 reaction with a highly functionalized lactamide electrophile and a unique difluoropiperidine nucleophile containing a pyridine -oxide moiety. Initial reactions with sulfonate leaving groups exhibited superb stereoselectivity, but yields were very low due to side reactions originated from competitive Kornblum reactions of the pyridine -oxide and the sulfonates. Markedly improved reaction profiles were achieved by including stoichiometric lithium triflate.

Chemical synthesis of scyllo-inosamine and catabolism studies in Sinorhizobium meliloti.

Rhizopines such as scyllo-inosamine (SIA) and L-3-O-methyl-scyllo-inosamine (3-O-MSI) play an intricate role as nutritional mediators during the establishment of the symbiotic relationship between legumes and rhizobia. The mechanism of action is not well understood. One challenge is the availability of rhizopines, which occur in only minute amounts in plant nodules.