New precursors for arylcarbenes. Photocycloelimination reactions of cyclic sulfites

Abstract

distilled and the residue was chromatographed as described for the preparation above, yielding 0.110 g (0.45 mmol) of 4, 0.417 g (2.24 mmol) of 3, and 1.796 g (9.54 mmol) of 2.C. Uv Irradiation.•-A homogeneous solution of 1.35 g (7.33 mmol) of S4N4, 200 ml of benzene, and 4.15 g (31.39 mmol) of tetrahydronaphthalene was irradiated for 206 hr at room temperature. After removal of the solvent under vacuum at room temperature, the residue was chromatographed. In addition to the unreacted tetrahydronaphthalene, 0.256 g (1.36 mmol) of 2 and 0.067 g (0.36 mmol) of 3 were obtained. Compound 4 was recovered in traces and identified by tic analysis.Reaction of S4N4 with 2.-A 0.748-g (3.97 mmol) sample of 2 in 20 ml of xylene was treated with 1.10 g (5.97 mmol) of S4N4 and the mixture was refluxed for about 8 hr under nitrogen atmosphere with stirring. After removal of the solvent by distillation at 20 Torr, the residue was chromatographed, yielding 0.059 g (0.24 mmol) of 4, 0.229 g (1.23 mmol) of 3, and 0.469 g (2.49 mmol) of 2.Reaction of 2 with Sulfur.-A mixture of 0.109 g (0.58 mmol) of 2 and 0.022 g (0.69 mmol) of sulfur was heated at 250-270°f or 2.5 hr. After cooling the residue gave after crystallization from methanol 0.078 g (0.42 mmol) of 3.

Carbamoyl Radical‐Mediated Synthesis and Semipinacol Rearrangement of β‐Lactam Diols

“…[ 34 ] Although less precedented in the literature, we were drawn to reports on the rearrangements of cyclopropyl diols to cyclobutanones by in situ formation of cyclic sulfites or sulfates, occurring at or below room temperature. [ 35 , 36 ]…”

Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

“…Similarly, we investigated the photochemistry of hydrobenzoin sulfite ( 9 ), which has been reported also to be a carbene precursor [ 16 ]. Because it has been shown in the case of cyclic carbonates that the application of milder reaction conditions enables the detection of reaction products that apparently decompose under harsher conditions, the original experimental conditions ( t = 15 h) were changed.…”

“…For instance, the photoextrusion of sulfur dioxide was carried out to facilitate the preparation of cyclophane derivatives [ 15 ]. The photochemistry of the corresponding cyclic sulfite esters is even less well known [ 16 – 18 ]. A report on the photochemistry of meso -hydrobenzoin sulfite undertaken about four decades ago stated that these compounds are also carbene precursors [ 16 ], in analogy to the results obtained with carbonate 1b .…”

“…The photochemistry of the corresponding cyclic sulfite esters is even less well known [ 16 – 18 ]. A report on the photochemistry of meso -hydrobenzoin sulfite undertaken about four decades ago stated that these compounds are also carbene precursors [ 16 ], in analogy to the results obtained with carbonate 1b . To provide further insight into the mechanism of the photoinduced cleavage of the cyclic sulfites, we examined the styrene glycol sulfite ( 8 ) and the hydrobenzoin sulfite ( 9 ); and we herein demonstrate that diradical intermediates are generated during the photoextrusion processes.…”

Palladium-Catalyzed Cross-Coupling Alkylation of Arenediazonium o-Benzenedisulfonimides

“…g Yields reported in brackets refer to the isolated and purified products 4 reported in the literature, 5 obtained by the reactions carried out using the corresponding tetrafluoroborates, hexafluorophosphates or hydrogen sulfates instead of salts 1. (Table 1; entries 14,15,17,18,24,25,28,29). We also recovered o-benzenedisulfonimide 8 (~80% yield) from all the reactions, which was suitable for reuse in the preparation of salts 1.…”