Phthalimide Hofmann rearrangement

The mechanisms are related to amide formation and Hofmann rearrangement, respectively. In the formation of phthalimide, only those proton transfers that occur along the pathway to the product are shown. 

Phenylethylamine has been made by a number of reactions, many of which are unsuitable for preparative purposes. Only the most important methods, from a preparative point of view, are given here. The present method is adapted from that of Adkins,1 which in turn was based upon those of Mignonac,2 von Braun and coworkers,3 and Mailhe.4 Benzyl cyanide has been converted to the amine by catalytic reduction with palladium on charcoal,5 with palladium on barium sulfate,6 and with Adams catalyst 7 by chemical reduction with sodium and alcohol,8 and with zinc dust and mineral acids.9 Hydrocinnamic acid has been converted to the azide and thence by the Curtius rearrangement to /3-phenyl-ethylamine 10 also the Hofmann degradation of hydrocinnamide has been used successfully.11 /3-Nitrostyrene,12 phenylthioaceta-mide,13 and the benzoyl derivative of mandelonitrile 14 all yield /3-phenylethylamine upon reduction. The amine has also been prepared by cleavage of N- (/3-phenylethyl) -phthalimide 15 with hydrazine by the Delepine synthesis from /3-phenylethyl iodide and hexamethylenetetramine 16 by the hydrolysis of the corre-... 

Likewise, the Hofmann-type rearrangement of substituted phthalimides 414 or succinimides 416 using a hypervalent iodine(III) reagent generated in situ from iodobenzene and mCPBA in alcohol in the presence of a base affords anthranilic acid derivatives 415 or amino acid derivatives 417, respectively (Scheme 3.167) [507]. 

Phthalimides 23 are transformed into a mixture of carbamates 25a and arylamines 25b by reaction with iodobenzene in the presence of /mCPBA and TsOH H20 (Scheme 9) [9]. The suggested mechanism implies the formation of imide-A, -iodane intermediates 24 which undergo alcoholysis followed by Hofmann-type rearrangement to yield 25. 

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