Dehydrohalogenation, photochemical

Decarbonylation, photochemical 885 Decarboxylation 605 Dehydrohalogenation 417 n-Delocalization 392 Demeton sulphones, mass spectra of 155... 

Laser molecular beam epitaxy, fabrication method for inorganic materials, 7 415t Laser photochemical vapor deposition (LPCVD), 19114-116 Laser pointers, 14 678 Laser-promoted dehydrohalogenation,... 

Azirines are also made by carbene addition to nitriles (89 — 90) and by thermal or photochemical (68JA2869) elimination of N2 from vinyl azides (e.g. 91 — 92). Vinyl azides are prepared by the Hassner reaction (68JOC2686, 71ACR9), where iodine azide is first added to an alkene and the resultant (3-iodoazide is dehydrohalogenated with base (Scheme 37) (86RTC456). 

Many synthetic routes have been found for silenes and germenes as depicted in Scheme 15. The most frequent synthetic methods used to produce the sterically protected, stable metallaalkenes are the photochemical [l,3]-sigmatropic shift of a silyl group to an oxygen atom in acylsilanes [route (ii)] and the dehydrohalogenation reactions of the corresponding halometallanes [route (vii)]. 

In order to determine the structure of the photochemical rearrangement product of carvone camphor in methanol, and to prove its structure, the research team of T. Gibson subjected the bicyclic carboxylic acid product to a degradation sequence, which commenced with the HVZ reaction, followed by dehydrohalogenation, dihydroxylation and glycol cleavage. 

A supplement entitled Lithium dicyclohexylamide" describes the preparation by Traynham e/ a/.34b of tran.v-cyclodecene by photochemical chlorination of cyclodecane to produce 1-chlorocyclodecane (4) and dehydrohalogenation of this substance with lithium dicyclohexylamide to form trans-cyclodecene in 70% yield. 

The aryl-aryl bond formation can be realized in the photochemical manner by irradiation of aryl iodides or bromides such as la which, by photo-dehydrohalogenation, give biaryls lla [90-92], Scheme 47. However, the photochemical synthesis of biaryls have also been performed as an intermolecular process [93]. The reactions are usually performed by irradiation of the given substrate in benzene or cyclohexane solution in the quartz-glass vessel, under the UV-light of... 

Intramolecular photochemical dehydrohalogenation reactions have featured prominently in heterocyclic and carbocyclic synthesis. The novel photocyclization of the enamine (110) was the key reaction in the synthesis of the antileukaemic lignan steganacin (111) (Scheme 36). This cyclization could have occurred by the SrnI mechanism. ... 

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