Synthesis of Chiral Thiazolo[3,4-a]pyrazine-5,8-diones

Methyl 3-Methyl-2H-azirine-2-carboxylate Photochemistry Studied by Matrix-isolation FTIR and DFT Calculations

“…45-47 kJ mol -1 (44.6 and 46.7 kJ mol -1 at the MP2/6-31G(d) and B3LYP/6-31G(d) levels of approximation, respectively) for the smallest member of the familysunsubstituted 2H-azirine. 1 The intrinsic strain of the three-membered ring system results in high reactivity of 2H-azirines, from which a variety of products can be obtained via thermal- [2][3][4][5] or photoexcitation 3,[5][6][7] or by reaction of 2H-azirines with nucleophiles 8,9 or electrophiles. 1 Therefore, 2H-azirines have been extensively studied as reagents in organic synthesis, and they are nowadays recognized as important intermediates in the preparation of acyclic and cyclic nitrogen-containing compounds.…”

“…1 The intrinsic strain of the three-membered ring system results in high reactivity of 2H-azirines, from which a variety of products can be obtained via thermal- [2][3][4][5] or photoexcitation 3,[5][6][7] or by reaction of 2H-azirines with nucleophiles 8,9 or electrophiles. 1 Therefore, 2H-azirines have been extensively studied as reagents in organic synthesis, and they are nowadays recognized as important intermediates in the preparation of acyclic and cyclic nitrogen-containing compounds. 6,[10][11][12][13][14][15][16][17] The thermal and photochemical excitation of 2H-azirines results in the formation of different products.…”

“…1 Therefore, 2H-azirines have been extensively studied as reagents in organic synthesis, and they are nowadays recognized as important intermediates in the preparation of acyclic and cyclic nitrogen-containing compounds. 6,[10][11][12][13][14][15][16][17] The thermal and photochemical excitation of 2H-azirines results in the formation of different products. It was shown that the C-N bond cleavage is favored by thermal treatment due to the unusual length of this bond, 1,18,19 while in general the C-C bond breakage is the dominant pathway resulting from photoexcitation of 2H-azirines.…”

“…6,[10][11][12][13][14][15][16][17] The thermal and photochemical excitation of 2H-azirines results in the formation of different products. It was shown that the C-N bond cleavage is favored by thermal treatment due to the unusual length of this bond, 1,18,19 while in general the C-C bond breakage is the dominant pathway resulting from photoexcitation of 2H-azirines. [5][6][7][20][21][22][23] In substituted 2H-azirines, the photochemical cleavage of the C-C bond gives rise to dipolar species (nitrile ylides), which can subsequently react with 1,3-dipolarophiles.…”

An improved synthesis of 10-isobornylsultone

“…Cleavage of the S-O bond of 1 with various nucleophiles gives rise to isoborneol sulfonamides 3, 5 isoborneol arylsulfones 4 6 and to 10-mercaptoisoborneol 5 7 which have all been frequently employed as chiral auxiliaries in asymmetric synthesis. [8][9][10][11] Sultone 1 has been previously synthesized by the sulfonation of camphene using acetic anhydride/fuming sulfuric acid, 2a or by the reduction of (+)-camphor-10-sulfonic acid with sodium borohydride followed by exposure of the intermediate sodium isobornylsulfonate salt to p-toluenesulfonyl chloride in pyridine. 2c,3,5,6a In a more recent report, Kaye obtained sultone 1 as a minor byproduct (4 % yield) during the reduction of phenyl (+)-camphor-10-sulfonate with sodium borohydride in H 2 O/EtOH at −8 o C, with the sultone 1 becoming the sole product (94 % yield) when the reduction was performed at 25 o C in absolute ethanol.…”