1,3‐Dipolare Addition von 2‐Benzonitrilio‐2‐propanid an 7‐Methylthieno[2,3‐c]pyridin‐1,1‐dioxid und Folgereaktionen

Abstract

1,3‐Dipolar Addition of 2‐Benzonitrilio‐2‐propanid to 7‐Methylthieno[2,3‐c]pyridine 1,1‐Dioxide and Subsequent Reactions The addition of dipole 2, generated photochemically from 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1), to 7‐methylthieno[2,3‐c]pyridine 1,1‐dioxide yields the pyrroline derivative 4 as a major product and regioisomer 5 in low yield. Compound 4 can be transformed into the pyrrolidine derivative 11 by ring opening, loss of SO2 and hydrogenation. Bromopyrroline derivative 14 gives either by dehydrohalogenation compound 18 or, by substitution, nitrile 17 or ethoxy derivative 19. Substitution of 14 and ring opening yields methoxypyrrole derivative 20, which gives access to the unstable hydroxypyrrole and hydroxypyrrolidine derivative 28 resp. 30. The vinylsulfone 18 is the starting material for addition‐ring‐cleavage reactions. Oxidation of pyrroline derivative 4 gives epoxy‐substituted N‐oxide 39 and di‐N‐oxide 40; and oxidative transformation of pyrrolidine derivative 11 yields the (hydroxymethyl)pyridylpyrrolidine derivative 45.

Asymmetric dearomatization of pyrrolesviaIr-catalyzed allylic substitution reaction: enantioselective synthesis of spiro-2H-pyrroles

“…Notably, the C]N bond of product 3g, bearing an aryl substituted imine, could not be reduced using sodium borohydride but it was transformed to amine 8 when sodium cyanoborohydride in acetic acid was employed (Scheme 1, eqn (5)). 13,15 In all processes, no notable loss of enantiomeric purity took place.…”