Benzylidene-t-butylamine

It is interesting to note that the hydrolysis of certain Schiff bases in weakly acidic solutions shows a similar mechanism (22). N-protonated substituted benzylidene-t-butylamines react with hydroxide ions to amino alcohols in the rate-determining step, and at lower pH the rate is almost entirely determined by attack of water on the protonated Schiff bases as a consequence of the rapidly decreasing concentration of hydroxide ions. 

The last few years have seen numerous applications of spin trapping to biological systems, and in these the trapping of hydroxyl radicals has assumed some importance. This work has been confined almost exclusively to nitrone scavengers 4 the fact that the hydroxyl adduct [6] of DMPO is much more persistent than that [7] of the commonly used nitrone, benzylidene-t-butylamine-N-oxide ( phenyl t-butyl nitrone ,3 or PBN) [3], may be due to a fragmentation reaction, with subsequent oxidation of the cr-hydroxybenzyl radical, as shown. 

The successful preparation of structural analogues of raised the hope that the chemistry of ammoxidation might also be reproduced in solution under mild laboratory conditions suitable for mechanistic studies. Thus we turned our attention to the critical C-N bond formation step to find out whether one can indeed produce ammoxidized product from a radical with a d imido metal center. For our studies diimido complexes (t-B iN)2M(OSiMe3)2 (M = Cr, Mo) [8,9] were selected as models for the postulated active sites in ammoxidation. Benzyl rather than allyl radicals were chosen for study since the products of allyl radical oxidation are not expected to be stable under our reaction conditions and because benzyl and allyl exhibit similar behavior in oxidation reactions [14]. Indeed, when a solution of (t-BuN)2M(OSiMe3)2 in toluene was heated at 100 C in the presence of benzoyl peroxide as a radical initiator, benzylidene-t-butylamine was obtained in up to 52% yield (Table I). The remaining organic products were C02> bibenzyl, and the expected isomeric distribution of (ortho meta para = 63 21 16) of methylbiphenyls. 

A soln. of 2-phenyl-4-methyl-2-oxazolin-5-one and N-benzylidene-n-butylamine in dry benzene refluxed 2 hrs. -> l-n-butyl-3-benzoylamino-3-methyl-4-phenyl-2-azetidinone. Y 50%. F. e. s. K. K. Prasad and T. Petrzilka, Helv. 58, 2504 (1975). 

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