Inter- and Innermolecular Reactions of Chloro(phenyl)carbene

Abstract

Supramolecular photolyses of 3-chloro-3-phenyl-3H-diazirine (8) were performed within cyclodextrin (CyD) hosts to determine whether these toroidal inclusion compounds could alter the reactivity of the ensuing carbene reaction intermediate, chloro(phenyl)carbene (9). Remarkably, no intramolecular products stemming from carbene 9 could be detected. Instead, modified CyDs were formed via so-called innermolecular reactions. Hence, diazirine 8 was photolyzed in various conventional solvents to gauge the intermolecular reactivity of carbene 9. Relevant results were used to rationalize the CyD innermolecular reaction products.

Three‐Membered Heterocycles. Structure and Reactivity

“…When the same substrate is photolyzed in an organic solvent, then the intermolecular process dominates, as illustrated by the cyclohexane adduct 779 [758]. This behavior is fairly general -the carbene derived from arylchlorodiazirine 780 also quantitatively traps THF when generated in that solvent [759].…”

Constrained Carbenes

“…[143] In solution, chloro(phenyl)carbene (54-Cl) inserts into solvent molecules to give 62; [144] indeed, no azine 57 is formed in either THF or alcohols. [143] In anhydrous alcohols, transformation of α-chloro ethers 62c,d provides the acetals 61c,d exclusively. However, base is required to neutralize the HCl byproduct and quench subsequent hydrolysis, which leads to benzaldehyde (PhCHO).…”

“…Finally, the formal carbene dimer 60 is formed in minor amounts (up to 5 %) only in nonpolar solvents. [143] Scheme 14. Generation of chloro(phenyl)carbene (54-Cl) and its subsequent reactions: RH = (a) CyD, (b) …”

“…[143] Photolysis of 55@CyD ICs in the solid phase produced azine 57, PhCHO, and HCl. But when the 55@CyD ICs were photolyzed as slurries in alkaline buffer (pH = 9.3), RP-HPLC and FAB MS revealed the presence of derivatized CyDs.…”

“…But when the 55@CyD ICs were photolyzed as slurries in alkaline buffer (pH = 9.3), RP-HPLC and FAB MS revealed the presence of derivatized CyDs. [143] Their structures were not fully ascertained, but FAB MS analysis ruled out 6…”