Radical Cyclization Approach to Spirocyclohexadienones
摘要:
Cyclization of an aryl radical at the ipso position of a p-O-aryl-substituted acetamide or benzamide generates oxindoles or quinolones bearing spirocyclohexadienone rings. This versatile reaction is applied to formal syntheses of the vasopressin inhibitor SR121463A and aza-galanthamine.
N‐Unsubstituted indol‐2‐one and 3,4‐dihydro‐2‐quinolinone compoundsbearingspirocycliccyclohexanone/cyclohexadienonerings can be accessed through a novel, improved method entailing the key radical spirocyclization of easily accessible N‐methoxymethyl (MOM)‐protected 2‐iodoanilides derived from 4‐azidobenzoic and 2‐(4‐azidophenyl)acetic acid.
Spirocyclohexylindolinone is used as a moiety in drug substances. A number of synthetic methods have been suggested to introduce the cyclohexyl ring into the C(3) position of N-protected indolinones, which complicates their preparation. A previously developed, consecutive, one-pot, multicomponent method is studied from a mechanistic aspect. We set out to clarify the details of this mechanism and the
The synthesis of spirooxindoles with a hypervalent iodine reagent depended on N-substituted benzanilide derivatives as starting materials. Reaction yields of benzanilides containing various N-substituents were discovered to relate to the cis and trans conformations of the amide bond by ab initio molecular orbital calculations at the B3LYP/6-31G(d,p) and MP2/6-31G(d,p) levels, including full geometry optimizations. The relationship between the reaction and conformation of the starting material by quantum chemical calculations was applied to the formal synthesis of SR121463.