Ethylene derivatives diazo compounds, with

Ethylene derivatives from diazo compounds with rearrangement s. 18, 862 1,2-Aminoethers from azomethinium salts... 

Synthesis of ethylene derivatives from diazo compounds with rearrangement... 

A large number of pyridazines are synthetically available from [44-2] cycloaddition reactions. In one general method, azo or diazo compounds are used as dienophiles, and a second approach is based on the reaction between 1,2,4,5-tetrazines and various unsaturated compounds. The most useful azo dienophile is a dialkyl azodicarboxylate which reacts with appropriate dienes to give reduced pyridazines and cinnolines (Scheme 89). With highly substituted dienes the normal cycloaddition reaction is prevented, and, if the ethylenic group in styrenes is substituted with aryl groups, indoles are formed preferentially. The cycloadduct with 2,3-pentadienal acetal is a tetrahydropyridazine derivative which has been used for the preparation of 2,5-diamino-2,5-dideoxyribose (80LA1307). 

Carbenes, generated by photolysis of di- and tetrachloro-o-quinone diazides, react with oxetane in a 1 3 ratio to afford 15-membered crown ethers. Benzocrown ether 675 was obtained in 16% yield (91CB1865). Derivatives of macrocyclic crown ethers with four or five oxygen atoms in a ring were synthesized by Cu(acac)2-catalyzed cyclization of a,polyethylene glycols. 20-26-Membered crown-4(5) ethers 676 were prepared from the above-mentioned diazo ketones with tri- or tetra-ethylene glycols in 7-26% yields. Treatment of l,8-bis(diazoacetyl)octane with dodecane-l,12-diol under the same conditions results in a mixture of 52-membered tetraether 646 (40%) and compound 645 (81CC616). 

Reaction of boranes with diazo compounds Synthesis of ketones from ethylene derivatives... 

Bis-oxazolines (Box), azabis-oxazolines (azaBox) and pyridine bis-oxazoline (PyBox) with a C2 symmetry form the great majority of various oxazoline-derived ligands which are used in immobilized catalytic cyclopropanation reactions (Scheme 36). For these reactions, immobilized ruthenium and copper complexes which are able to form carbene intermediates have been tested. Most of the time, the reaction involved styrene and ethyl diazoacetate (EDA). However other alkenes (diphenyl ethylene. ..) and other diazo compounds (i.e. tertiobutyl and ethyl 2-phenyl diazoacetate) have also been investigated (Scheme 36). 

By far the best source for 3a is (trimethylsilyl)diazomethane (19). It has already been mentioned that gas-phase pyrolysis of 19 alone yields products which are derived from intramolecular carbene reactions such as 1,3-C,H insertion and silylcarbene-to-silene rearrangement (see equation 20). Also, copyrolysis of 19 with alcohols or benzaldehyde allowed one to trap the silene but not the carbene 33 (see equation 5). Furthermore, solution photolysis of 19 in the presence of alcohols or amines did not give the X,H insertion products of the carbene but rather trapping products of the silene . On the other hand, photochemically generated carbene 3a did undergo some typical intermolec-ular carbene reactions such as cyclopropanation of alkenes (ethylene, frani-but-2-ene, but not 2,3-dimethylbut-2-ene, tetrafluoroethene and hexafluoropropene), and insertion into Si—H and methyl-C—H bonds (equation 39). The formal carbene dimer, trans-1,2-bis(trimethylsilyl)ethene, was a by-product in all photolyses in the presence of alkenes it is generally assumed that such carbene dimers result from reaction of the carbene with excess diazo compound. 

Triphenylcarbonium perchlorate Reactions with diazo compounds Sym. ethylene derivatives and azines by dimerization... 

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