Expeditious copper-catalyzed conjugate 1,4-addition of bromo[2-(1,3-dioxolan-2-yl)ethyl]magnesium to alpha,beta-cycloalkenones and subsequent transformations

Expeditious CuI-catalyzed conjugate 1,4-addition of bromo[2-(1,3-dioxolan-2-yl)ethyl]magnesium to the five-, six-, seven-, and eight-membered alpha,beta-cycloalkenones is described. The reaction times are decreased dramatically compared to CuBr-(CH(3))(2)S catalysis. The resulting ketoacetals were subsequently cyclized to bicyclic beta-hydroxy ketones and alpha,beta-enones, followed by further transformations.     

Influence of the heterocyclic side ring on orientation during nitrations of 1,2-alkylenedioxy-annelated benzenes and their mononitro derivatives

Nitration of 1,2-alkylenedioxybenzenes 1 furnished the respective nitro derivatives 3 and 4 in the relative ratios: 4a:3a /100:trace, 4b:3b /98:2.4, 4c:3c /86:14, 4e:3e /91:9 and 4f:3f /99:1.3. Nitration of 4 gave 5a:6a:8a /0:0:100, 5b:6b:8b /7.7:3.2:89, 5c:6c:8c /23:12:65, 5d:6d:8d /14:74:12, 5e:6e:8e /27:18:55 and 5f:6f:8f /23:7.0:70. Nitration of the isomeric 3 afforded the dinitro products 5, 6 and 7 in the following relative ratios: 5a:6a:7a /92:8:0, 5b:6b:7b /80:20:0, 5c:6c:7c /69:20:1 1, 5d:6d:7d /45:19:36, 5e:6e:7e /37:57:5.9 and 5f:6f:7f /64:36:0. Nitration of 3-nitro-1,2-dimethoxybenzene ( 9 ) furnished: 10:11 /63:37. Orientation as a function of the heterocyclic ring-size is discussed.     

Transformations on 2,3,4,5-tetrahydrobenzo[b][1,4]-dioxocin leading to substituted ortho-nitroaryl azides,benzofuroxans, benzofurazans and related compounds

Nitration of the acetamido-nitrobenzodioxocins 10 , prepared from the corresponding amino derivatives 9 , led to the acetamido-dinitrobenzodioxocins 11 , hydrolysis of which furnished the corresponding amines 13 . Preparation of the dinitroazides 18 and acetamido-nitroazides 21 as precursors to substituted dioxocino-annelated benzofuroxans is described. Thermolysis of the dinitro-azido derivatives 18a,c,e and/or direct nitration of the unsubstituted benzofuroxans 1a, 2a afforded the isomeric nitrobenzofuroxans 1b, 2b,c . Thermolysis of the acetamido-nitroazides 21 gave the acetamidobenzofuroxans 1d, 2d,e . All benzofuroxans were deoxygenated to the corresponding benzofurazans 3b,d, 4b-e . Some aspects of electrophilic and nucleophilic aromatic substitution are discussed.     

Conversion of acetamido- and nitro-substituted ortho-azidonitro derivatives of 2,3,4,5-tetrahydrobenzo [b][1,4]dioxocin to the corresponding furoxans and furazans in the gas phase

Electron impact ionization of the five isomeric 2,3,4,5-tetrahydro-9-azido-7,8-dinitro-, 2,3,4,5-tetrahydro-8-azido-7,9-dinitro-, 2,3,4,5-tetrahydro-8-azido-7,10-dinitro-, 2,3,4,5-tetrahydro-7-azido-8,9-dinitro-, 2,3,4,5-tetrahydro-7-azido-8,10-dinitro- and the related 2,3,4,5-tetrahydro-7-acetamido-8-azido-9-nitro-, 2,3,4,5-tetrahydro-7-acetamido-9-azido-8-nitro-, 2,3,4,5-tetrahydro-9-acetamido-7-azido-8-nitro-, 2,3,4,5-tetrahydro-10-acetamido-7-azido-8-nitrobenzo[b] [1,4]dioxocin derivatives furnished, after elimination of nitrogen, the corresponding nitro and acetamido dioxocino-annelated benzofuroxans. Further loss of oxygen from the latter afforded the corresponding benzofurazans. It was shown in two cases that these processes occur primarily upon electron impact ionization, without excluding some small fraction undergoing a thermal degradation process. The proposed fragmentation patterns are supported by high-resolution and mass-analyzed ion kinetic energy spectroscopic data. Similar work on the unsubstituted 6,7-dihydro[1,4]dioxino[2,3-f]- and 7,8-dihydro-6H-[1,4]dioxepino[2,3-f]-2,1,3-benzoxa-diazole 1-oxide reveal that loss of oxygen from the molecular ion to furnish the corresponding benzofurazans is the result of electron impact ionization (at least in part).     

Preparation of benzofuroxans and benzofurazans of 2,3,4,5-tetrahydrobenzo[b] [1,4]dioxocin and related compounds

The novel benzofuroxans 1d, 2 and benzofurazans 3,4 have been prepared in good yields. Nitration of 5c furnished the mononitro-derivatives 6a and 6b in the unusually high relative ratio 6a:6b of 23:77. Direct nitration of 5c or 6a + 6b afforded the unexpected dinitro-derivative 8b as the major product along with the isomeric 8a, 8c and 8d . Improvement in the yield of 5c (to 86%) is reported.