A new cross-conjugated mesomeric betaine

Abstract

Cross-conjugated mesomeric betaine (CCMB) has been defined as the dipolar species in which positive and negative charges are exclusively restricted to different parts of the molecule. A new CCMB isoconjugate with odd non-alternant hydrocarbon anion is reported.

A cascade reaction of imidazo[1,2-a]pyridines with maleic anhydride: formation of cross-conjugated mesomeric betaines

“…The reaction of imidazo[1,2-a]pyridine with maleic anhydride proceeded almost similarly to its reaction with DMAD 12 , i.e., the reaction generates a 1,4-dipole (14) which subsequently reacts with a second molecule of maleic anhydride to form 15. Nevertheless, there are some distinct differences between the two reactions.…”

Unique Pseudo-Cross-Conjugated Mesomeric Betaines via an Iodate-Promoted Reaction of 3,3-Difluorocyclopropenes, Pyridines, and Anilines

“…Unambiguity of cyanosilylation of the betaine 57 allowed us to characterize the reaction product without isolation as 5-cyano-3-phenylamino-7-trifluoromethyl-1-trimethylsilyloxyindolizine 97 (Scheme 8). We rationalized the reaction mechanism, which includes O − −C5 addition of TMSCN, followed by [1,9]H-shift. The addition starts from the nucleophilic attack of the cyanide ion, since no reaction was observed when we changed TMSCN to TMSCl in the same reaction conditions.…”

“…It was found that their C3 position undergoes a thermodynamically controlled intramolecular nucleophilic attack, while the C5 position is prone to reversible addition of O-and S-nucleophiles. With TMSCN as a C-nucleophile, subsequent silylation of exocyclic oxygen at C1 occurs, giving 5-cyano-3-phenylamino-1-trimethylsilyloxyindolizine after [1,9]H-shift. Hydroperoxide-promoted oxygenation at the C5 position affords novel 1,5-dioxo-3-arylamino-1,5-dihydroindolizines.…”

“…While conjugated HMBs are well known, some subclasses of cross-conjugated and especially pseudo-cross-conjugated HMBs are presented by a few examples at best. In recent years, the cross-conjugated and pseudo-cross-conjugated HMBs have attracted much attention due to their applications in developing new materials . Exceptional photophysical properties of the HMBs make them very attractive for applications in nonlinear optics .…”

“…In recent years, the cross-conjugated and pseudo-cross-conjugated HMBs have attracted much attention due to their applications in developing new materials. 9 Exceptional photophysical properties of the HMBs make them very attractive for applications in nonlinear optics. 10 Exploration (synthetic methodology and properties) of such limited subclasses of HMBs is important and can represent an independent interest in organic chemistry.…”