[Difluoro(phenylsulfanyl)methyl]trimethylsilane (PhSCF2SiMe3) underwent a fluoride‐induced nucleophilic addition to the carbonyl group of Weinreb amides to provide the corresponding difluoro(phenylsulfanyl)methyl ketones. These were converted into difluoromethyl ketones through selective reductive cleavage of the phenylsulfanyl group. The reaction of o‐alkynyl Weinreb amides derived from benzoic acid derivatives resulted in the formation of cyclized products through a 5‐exo‐dig cyclization.

The activity of the non-heme iron enzyme nitrile hydratase (Fe-NHase) is modulated by nitric oxide (NO). The inactive (dark form) NO-bound enzyme is activated when exposed to light via the release of NO from the iron center. In order to determine whether oxygenation of active site Fe-bound Cys-S centers are involved in this process of NO regulation, a model complex (Et(4)N)[(Cl(2)PhPepS)Fe(NO)(DMAP)] (8) has been synthesized and structurally characterized. Complex 8 does not exhibit any NO photolability. However, following oxygenation of the Fe-bound thiolato-S centers to sulfinates (with the aid of oxaziridine), the resulting complex (Et(4)N)[(Cl(2)PhPep{SO(2)}(2))Fe(NO)(DMAP)] (9) releases NO readily upon illumination with visible light. Spectroscopic properties of 8 and 9 confirm that these species do mimic the active site of Fe-NHase closely, and the results indicate that NO photolability is related to S-oxygenation. Results of density functional theory and time-dependent DFT studies on both 8 and 9 indicate that S-oxygenation weakens Fe-S bonding and that strong transitions near 470 nm transfer an electron from a carboxamido-N/sulfinato-SO(2) MO to a dpi(Fe)-pi*(NO)/d(z)2(Fe)-sigma*(NO) antibonding orbital in 9. In case of 8, strong S-Fe-NO bonding interactions prevent the release of NO upon illumination. Together, the results of this work strongly suggest that oxygenated Cys-S centers play an important role in the process of NO regulation of Fe-NHases.

In order to determine the origin of the NO photolability of the active site of Fe-containing nitrile hydratase (Fe-NHase), a model complex of the NO-bound active site (dark form) has been isolated and structurally characterized. The model, NEt(4)[(Cl(2)PhPepS)Fe(NO)(DMAP)] (2), is derived from a tetradentate ligand comprising carboxamido N and thiolato S donor centers much like the donors present in the active site of Fe-NHase. This {Fe-NO}(6) nitrosyl effectively mimics the NO-bound active site in terms of structural and spectroscopic parameters. However, this model lacks the key property of NO photolability. Interestingly, S-oxygenation of the model complex results in formation of Na[(Cl(2)PhPep{SO(2)}(2))Fe(NO)(DMAP)] (3), in which the -S donors are oxygenated to -SO(2) moieties, and this species exhibits NO photolability. These results indicate that S-oxygenation could be the key reason for the observed NO photolability of the active site of the dark form of Fe-NHase.

Electrophilic difluoro(phenylthio)methylation of allylsilanes has been achieved using bromodifluoro(phenylthio)methane (PhSCF2Br) and silver hexafluoroantimonate (AgSbF6). The structural assignment and observation of α-fluorocarbocation were substantiated by NMR and theoretical calculations. Detailed mechanistic and electronic studies have provided a fundamental understanding of the reactivity and stability of the difluoro(phenylthio)methylium cation (PhSCF2(+)).

Bismuth(III) trifluoromethanesulfonate [Bi(OTf)3] mediated mild electrophilic aromatic formylation utilizing difluoro(phenylsulfanyl)methane (PhSCF2H) as a formylating agent in hexafluoro‐2‐propanol (HFIP) as a recyclable ionizing solvent has been developed. The active formylating species was generated via C−F bond cleavage and was characterized to be a bis(phenylsulfanyl)methyl cation by experimental and computational 1H and 13C NMR.