Ring synthesis inversion

H-Azepine, 2-allyloxytetrahydro-Claisen rearrangement, 7, 508 3H-Azepine, 2-amino-acylation, 7, 511 effect of acidification, 7, 510 nucleophilic displacement reactions, 7, 514 synthesis, 7, 533, 535 3H-Azepine, 2-amino-7-bromo-synthesis, 7, 529 3H-Azepine, 2-anilino-ring inversion, 7, 495-499 structure, 7, 533... 

H-Azepine, 2,6,7-tri(methoxycarbonyl)-ring inversion, 7, 499 Azepine-1-carboxylic acid tricarbonylruthenium complexes, 7, 523 1 H-Azepine-2,3-dicarboxylic acid, 4,7-dihydro-6-phenyl-diethyl ester synthesis, 7, 539-540 1 H-Azepine-3,6-dicarboxylic acid... 

Azetidine, 7V-bromo-, 7, 240 Azetidine, AT-r-butyl- N NMR, 7, 11 Azetidine, AT-t-butyl-3-chloro-transannular nucleophilic attack, 7, 25 Azetidine, 3-chloro-isomerization, 7, 42 Azetidine, AT-chloro-, 7, 240 dehydrohalogenation, 7, 275 Azetidine, 7V-chloro-2-methyl-inversion, 7, 7 Azetidine, 3-halo-synthesis, 7, 246 Azetidine, AT-halo-synthesis, 7, 246 Azetidine, AT-hydroxy-synthesis, 7, 271 Azetidine, 2-imino-stability, 7, 256 Azetidine, 2-methoxy-synthesis, 7, 246 Azetidine, 2-methyl-circular dichroism, 7, 239 optical rotatory dispersion, 7, 239 Azetidine, AT-nitroso-deoxygenation, 7, 241 oxidation, 7, 240 synthesis, 7, 246 Azetidine, thioacyl-ring expansion, 7, 241 Azetidine-4-carboxylic acid, 2-oxo-oxidative decarboxylation, 7, 251 Azetidine-2-carboxylic acids absolute configuration, 7, 239 azetidin-2-ones from, 7, 263 synthesis, 7, 246... 

Aziridine, 2,3-diphenyl-l-(2,4,6-trinitrophenyl)-irradiation, 7, 61 Aziridine, 1,2-divinyl-rearrangement, 7, 539 Aziridine, 2,3-divinyl-rearrangement, 7, 42, 65, 539 Aziridine, N-ethyl-inversion, 7, 6 Aziridine, 2-halo-reactions, 7, 74 Aziridine, A/-halo-invertomers, 7, 6 Aziridine, 2-methyl- N NMR, 7, 11 Aziridine, methylene-ring-ring valence isomerizations, 7, 22 synthesis, 7, 92 Aziridine, iV-nitroso-reactions, 7, 74 Aziridine, iV-phosphino-inversion, 7, 7 Aziridine, 1-phthalimido-UV irradiation, 7, 62-63 Aziridine, l-(3-thienyl)-2-vinyl-rearrangement, 4, 746 Aziridine, 7V-trimethylsilyl-inversion, 7, 7 Aziridine, 1,2,3-triphenyl-irradiation, 7, 61 Aziridine, vinyl-isomerization, S, 287 Aziridinecarboxylic acid ring expansion, 7, 262 Aziridine-2,2-dicarboxylic acid, 1-methoxy-diethyl ester... 

Intermolecular [4C+2S] cycloaddition reactions where the diene moiety is contained in the carbene complex are less frequent than the [4S+2C] cycloadditions summarised in the previous section. However, 2-butadienylcarbene complexes, generated by a [2+2]/cyclobutene ring opening sequence, undergo Diels-Alder reactions with typical dienophiles [34,35] (Scheme 59). Also, Wulff et al. have described the application of pyranylidene complexes, obtained by a [3+3] cycloaddition reaction (see Sect. 2.8.1), in the inverse-electron-demand Diels-Alder reaction with enol ethers and enamines [87a]. Later, this strategy was applied to the synthesis of steroid-like ring skeletons [87b] (Scheme 59). 

Posner G. H., Anjeh T. E. N., Carry J. C., French A. N. A New and Efficient Asymmetric Synthesis of an A-Ring Precursor to Physiologically Active 1-a-Hydroxyvitamin D3 Steroids Proc. - NOBCChE 1994 21 383-389 Keywords inverse electron-demand Diels-Alder cycloadditions, (S)-lactate and Lewis acids (-)-Pr(hfc)3 with benzyl vinyl ether... 

Photocycloaddition of Alkenes and Dienes. Photochemical cycloadditions provide a method that is often complementary to thermal cycloadditions with regard to the types of compounds that can be prepared. The theoretical basis for this complementary relationship between thermal and photochemical modes of reaction lies in orbital symmetry relationships, as discussed in Chapter 10 of Part A. The reaction types permitted by photochemical excitation that are particularly useful for synthesis are [2 + 2] additions between two carbon-carbon double bonds and [2+2] additions of alkenes and carbonyl groups to form oxetanes. Photochemical cycloadditions are often not concerted processes because in many cases the reactive excited state is a triplet. The initial adduct is a triplet 1,4-diradical that must undergo spin inversion before product formation is complete. Stereospecificity is lost if the intermediate 1,4-diradical undergoes bond rotation faster than ring closure. 

---