An effective one-pot access to polynuclear dispiroheterocyclic structures comprising pyrrolidinyloxindole and imidazothiazolotriazine moieties via a 1,3-dipolar cycloaddition strategy

Abstract

An effective and highly regio- and diastereoselective one-pot method for the synthesis of new polynuclear dispiroheterocyclic systems with five stereogenic centers (dispiro[imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-6,3′-pyrrolidine-2′,3′′-indoles]) comprising pyrrolidinyloxindole and imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine moieties has been developed. The method relies on a 1,3-dipolar cycloaddition of azomethine ylides generated in situ from isatin derivatives and sarcosine to 6-benzylideneimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7-diones.

A Diastereoselective Synthesis of Dispiro[oxindole-cyclohexanone]pyrrolidines by 1,3-Dipolar Cycloaddition

“…The exo -channel ( TS exo ) is not beneficial, because of the repulsion of the cyclohexane core and the oxindole fragment. The results of our control experiment are confirmed by literature data [ 9 , 10 , 11 ]. Under similar conditions, biarylidenecyclohexanones 1a – f ( Scheme 5 ) in the reaction with sarcosine ylide give rise to a mixture of 2 and 3 cycloaddition products at two reactive multiple bonds.…”

“…Up to the present time, a large amount of data has been accumulated on the regio- and stereochemistry for dipolarophiles of different nature, including acrylates, chalcones, and nitrostyrenes, so it is known that ylides generated from sarcosine react regioselectively with the most electrophilic center of the dipolarophile [ 9 , 10 , 11 , 12 , 13 ] (path I , Scheme 1 ) with the formation of endo -adducts in good yields. Exceptions are nitrostyrene, that exhibits a reversed addition selectivity (path II , Scheme 1 ) [ 14 ].…”

5‐Indolylidene‐2‐iminothiazolidin‐4‐ones – Convenient Starting Compounds for Stereoselective Synthesis of Novel Dispirooxindole Derivatives

“…Finally, we have studied 1,3‐dipolar cycloaddition reaction of some oxindolylidene derivatives 5 and 6 with azomethine ylides generated in situ from paraformaldehyde and N‐alkyl amino acids using a procedure similar to one described earlier [3,10] . 1,3‐Dipole was thermally generated by a reaction between paraformaldehyde and an amino acid in boiling solvent via formation of an iminium intermediate which underwent cyclization with subsequent loss of CO 2 [10,11] .…”

Engaging Isatins in Multicomponent Reactions (MCRs) – Easy Access to Structural Diversity

“…The azomethine ylides derived from isatin derivatives and sarcosine were used (Scheme 12A). Despite long reaction times the overall yields were moderate to good [34] …”