Junichi Matsumoto

Ring expansion of nitrogen-containing chloromethylheteroalicycles via aziridinium intermediates

The nucleophilic reaction of NaN3 with the chloromethylheteroalicycles, 4-benzyl-3chloromethyl-morpholine 5a, -tetrahydro-4H-1,4-thiazine 5b, -1-methylpiperazine 5c and 1-benzyl-2-chloromethylpiperidine 5d, gave the ring-expanded compounds 6-azido-4-benzylhexahydro-1,4-oxazepine 11a and its analogues 11b–d along with the normally substituted compounds 3-azidomethyl-4-benzylmorpholine 10a and its analogues 10b–d in varying ratios. LUMO frontier electron densities of the reaction centres indicated that the reaction proceeded via the aziridinium intermediate 9 and accounted for the predominance of the reaction product 10 or 11.

Medium-sized cyclophanes. Part 46.1 The preparation and novel [3.3]- and [1.5]-sigmatropic rearrangements of [n.2]cyclophanes having a spiro skeleton†

Oxidation of dihydroxy[n.2]metacyclophanes 4 with K3[Fe(CN)6] affords in good yield the intramolecular O–C coupling products 5 having a spiro skeleton. Variable temperature 1H NMR measurements indicate that compounds 5 are interconvertible by thermal [3.3]sigmatropic rearrangement. The free energies for the [3.3]sigmatropic rearrangement increase with increasing length of the methylene bridge in compounds 5. The substituent effect on the [1.5]sigmatropic rearrangement of [2.2]cyclophanes 3 having a spiro skeleton is also discussed.

Medium-sized Cyclophanes. Part 40.1Generation of a Bis(o-quinone methide) from[n.2]Cyclophanes having a Spiro Skeleton and theirTrapping Reaction with Nucleophiles and Dienophiles

Spiro compounds 2, obtained from the oxidation of dihydroxy[n.2]metacyclophanes 1 with K 3 Fe(CN) 6 , readily generate a bis(o-quinone methide) 3 with mild heating which is trapped with nucleophiles and dienophiles to give diarylalkanes 4–6 and [4+2] cycloadducts 8, respectively.