Preparation of Thioanisole Biscarbanion and C–H Lithiation/Annulation Reactions for the Access of Five-Membered Heterocycles

Abstract

The synthesis, isolation, and X-ray structure of a thioanisole-based trilithium complex are reported. On the basis of the double-lithiation strategy, two novel synthetic methodologies have been developed under mild reaction conditions (room temperature): (1) reactions of lithiated thioanisoles with nitriles give benzoisothiazoles via a [3 + 2]-type of approach with two new bond formations and (2) formation of benzothiophenes from thioanisoles and amides through a [4 + 1] pattern forming 4 new chemical bonds.

Corannulenes with Electron‐Withdrawing Substituents: Synthetic Approaches and Resulting Structural and Electronic Properties

“…Monosubstituted cyanocorannulene 25 can be generated in as ubstitution reaction of bromocorannulene with copper(I) cyanidei nr efluxing DMF (Scheme 14). [39] The yield for this transformation is moderate. The authorsu se cyanocorannulene (25)f or further functionalization to yield ab enzoisothiazole.…”

“…Despite the prediction of interesting electronic properties (see Figure ), only two compounds have been reported in the literature. Monosubstituted cyanocorannulene 25 can be generated in a substitution reaction of bromocorannulene with copper(I) cyanide in refluxing DMF (Scheme ) . The yield for this transformation is moderate.…”

“…As can be expected, the introduction of nitrile substituents allows further functionalization. For example, the cyano group can be used to build up heterocyclic compounds, as mentioned before for 25 . However, it is also possible to generate other electron‐withdrawing groups.…”

“…For example, the cyano group can be used to build up heterocyclic compounds, as mentioned before for 25. [39] However,i ti sa lso possible to generate other electron-withdrawing groups. For example, this can be achieved if tetracyanocorannulene 26 is hydrolyzed, dehydrated, and finally transformed into fused imides 27 a and 27 b, which bear ap entafluorophenyl and a2 ,2,2-trifluoroethyl substituent at the nitrogen atom, respectively (Scheme 15).…”

“…Preparationo fc yanocorannulenes 25 and 26. [39,40] Scheme15. Synthesis of imide-substituted corannulenes 27 and 29.…”