Formation of Condensed 1<i>H</i>-Pyrrol-2-ylphosphonates and 1,2-Dihydropyridin-2-ylphosphonates via Kabachnik–Fields Reaction of Acetylenic Aldehydes and Subsequent 5-<i>exo</i>-<i>dig</i> or 6-<i>endo</i>-<i>dig</i> Cyclizations
Kabachnik–Fields reactions of various carbocyclic or heterocyclic acetylenic aldehydes together with subsequent Lewis acid catalyzed cyclizations have been studied. It was found that 5-exo-dig versus 6-endo-dig cyclization mode strongly depends on the structure of starting materials. Thus, nonaromatic acetylenic α-anilinomethylphosphonates underwent gold(III)-catalyzed or iodine-mediated 5-exo-dig
An efficient enantioselective synthesis of cyclic α-aminophosphonates via multicomponent reactions of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate has been developed with the use of a chiral silver spirocyclic phosphate as the catalyst. This protocol provides straightforward access to a series of chiral C1-phosphonylated 1,2-dihydroisoquinoline derivatives with high yields (up to 99%) and