Irradiation of 5 : 5-dimethyl-Al-pyrroline 1 -oxide yields the bicyclic oxaziran (IV), also obtained by oxidation of 5 : 5-dimethylpyrroline with aqueous hydrogen peroxide. Thermal rearrangement of the oxaziran (IV) leads to 5 : 5-dimethylpyrrolid-2-oneJ whereas acidic hydrolysis yields laevulic aldehyde.Investigation of a reported 3-hydroxyoxaziran shows it to be the isomeric hydroxamic acid. RECENT investigations l s 2 have revived interest in compounds containing the threemembered carbon-nitrogen-oxygen (oxaziran) ring (I) , a formulation at one time suggested for the nitrones (azomethine N-oxides) (11) only to be subsequently discarded. The oxazirans and the azomethine N-oxides might be regarded as electronic tautomers and, indeed, irradiation of nitrones can yield o x a ~i r a n s , ~ thermal decomposition of which regenerates the original n i t r ~n e s . ~In the course of our work on Al-pyrroline l-oxides we irradiated 5 : 5-dimethyl-A1pyrroline l-oxide 5 (111), whereupon the nitrone was converted into an isomer to which we assign the oxaziran structure (IV). The same material was obtained on oxidation of 5 : 5-dimethyl-Al-pyrroIine with aqueous hydrogen peroxide.The product is assigned structure (IV) on the basis of its analysis and active-oxygen content (cf. ref. l ) , and the absence of ultraviolet absorption (in ethanol), of infrared maxima (liquid film) in the N-H and double-bond regions, and of basic properties. The * Part 11, preceding paper.

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Brown, Clark, Lamchen, and Todd: 427. Experiments towards the Bynthesis of Corrins. Part V P The Dimerisation of Al-Pyrroline 1 -Oxides to 2 4 '-Hydroxypyrrolidin-2'-yl)-A1-pyrroline 1 -Oxides. By R. F. C. BROWN, V. M. CLARK, M. LAMCHEN, and SIR ALEXANDEH TODD.Under certain conditions, sodamide in liquid ammonia catalyses the dimerisation of Al-pyrroline 1-oxides to 2 : 2'-dipyrrolidinyl derivatives. In the case of 5 : 5-dimethyl-A1-pyrroline l-oxide a degradative proof of structure of the dimer is presented.THE corrin nucleus (I), upon which the macrocyclic component of the vitamin B,, chromophore is based, is distinguished from the closely related porphyrins not only by the difference in oxidation level but also by the absence of a meso-carbon atom linking rings A and D. In exploring possible synthetic routes to the corrins we have therefore examined methods for the elaboration of intermediates related to 2 : 2'-bipyrrolidinyl (11), in addition to these based on dipyrrolidin-2-ylmethane (111). Derivatives of the latter formed the subject of the preceding paper in which the base-catalysed aldol-type reactions of various Al-pyrrohe l-oxides (IV) were recorded. n -C H & J N (III) HThe nitrone group (V), although capable of undergoing nucleophilic addition at the carbon atom,2 might also be expected to exhibit electrophilic reactivity a t that site as expressed by the canonical form (VI); indeed, the N-oxide linkage in pyridine l-oxide is highly polarisable in both directions 8 and electropkilic substitution in the 4-position of pyridine oxide occurs r e a d i l~.~ Moreover, in the aliphatic series, the anion of nitromethane (V; R = H, R' = 0-) dimerises by an addition equivalent to that of (V) to (VI) to yield, ultimately, nitroacetic acid; ti and the adduct (V; R = H, R' = Ph) of formaldehyde and C,,H,,N, requires equiv., 98). The oil had pK,, = 6.95 and pK, = 10.3.

The optical isomers of 2-(2-ethoxyphenoxymethyl)tetrahydro-1,4-oxazine (viloxazine) and 2-(3-methoxyphenoxymethyl)tetrahydro-1,4-oxazine have been prepared and absolute configurations have been assigned. In their action on the central nervous system the S isomers are at least ten times more potent than the R isomers. The intermediate 4-benzyl-2-(p-toluensulfonyloxymethyl)tetrahydro-1,4-oxazine has been resolved. Its isomers provide a convenient starting point for the preparation of optical isomers of viloxazine analogues of known configuration.

Some 2-aryloxymethyl-2,3,5,6-tetrahydro-1,4-oxazines have been shown to possess marked antidepressant activity. The 1,4-oxazines were synthesized by lithium aluminum hydride reduction of the readily available 6-aryloxymethyl-2,3,5,6-tetrahydro-1,4-oxazin-3-ones. High antidepressant activity was associated with ortho substitution of the 2-phenoxymethyl group and with 1,4-oxazines devoid of 4-substituents.