Von-Braun-type degradation

The tertiary amines 303 and the acid chlorides 304 (X = Cl) initially formed acylammonium salts 305, which underwent a von Braun type degradation by an attack of the nucleophilic chloride ion at the allyl system to give allyl chlorides 306/307 and carboxylic acid amide functions. 

Demethylation at the nitrogen in position 6 could be realized by new modifications of the von Braun degradation. The 6-nor-6-cyano derivatives 46, obtained in the usual way by the action of cyanogen bromide on the parent compounds, could be reduced directly with zinc in acetic acid in good yield (46) to the 6-nor compounds (47). An alternative procedure was published independently by a Japanese group (47), using a two-step process via a urea-type compound 48. 

Biogenetically, daphnilactone-B (36) is regarded as a plausible intermediate between daphniphylline-type and yuzurimine-type alkaloids. Thus, daphnilactone-B (36) was converted to a daphniphylline-type compound (38, mp 166-168° C22H3302N) via a bromocyanamide [39, mp (dec) 210°] and a debromocyanamide (40, mp 208-212°), as shown in Scheme V. The structure of this daphniphylline-type compound 38 was confirmed by its mass, IR, and NMR spectra coupled with von Braun degradation of 38 leading to the formation of a new... 

Voachalotine (49) (Scheme 14) undergoes " von Braun degradation to give an ether (50) of the taberpsychine type. Oxidation of this alkaloid with... 

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