Nitrosation, hydrolytic

The treatment of cyclic enol ethers with alkyl nitrites or with nitrosyl chloride gave oximino macrolides in almost quantitative yield [100] [102], The furan derivatives are inert to hydrolytic nitrosation [100]. 

The hydrolytic stability of the [Co(diCLsar)]3+ cation toward conversion to the [Co(diHOsar)]3+ dihydroxysarcophaginate is due to the difficulty of forming a carbocation at a planar bridgehead position. It was noted that the nitrosation of [Co(diAMsar)]3+ sarcophaginate occurring without rearrangement involves compe-... 

These facts suggest that the imidazole ring in compounds 86, 330, 334 and 617 is first reversibly covalently hydrated in the acid medium to form 638, and then a hydrolytic ring opening occurs to provide intermediate 639. Then A -nitroso compound 640 forms and ring closes to afford l-methyl-l,2,3-triazolo[4,5-c]pyridine 637 (80KG121). The A -nitrosation occurs with nitrogen oxides formed from nitric acid reduction. 

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