Oxetanes, ring-opening nitration

Dinitrate esters from the ring-opening nitration of oxetanes with dinitrogen pentoxide... 

The reaction of 3-phenyloxetane (10) with nitric acid in dichloromethane and trichloromethane under anhydrous conditions has been investigated.35 Quantitative conversion into 2-(nitrophenyl)propane-l,3-diol dinitrates occurs. The substrate reacts through its majority hydrogen-bonded complexed form initially by a mixture of aromatic nitration and oxetane ring opening. The nitration, perhaps surprisingly, proceeds at a rate comparable to that of / -dichlorobenzene. 

Archibald and Manser prepared NF2-substituted analogs of pentaerythrityl esters (such as PETN). Specifically, 3-(difluoraminomethyl)-3-methyloxetane (14) and 3,3-bis(difluoraminomethyl)oxetane (15) [101] were subjected to ring-opening nitration by nitric acid (Scheme 12), giving corresponding 1,3-propanediyl dinitrate esters in quantitative yield [105,106]. As neopentyl difluoramines, the products had superior stabihty compared to many other mono(difluoramino)alkyl-substituted compounds. 2,2-Bis(difluoraminome-thyl)-l,3-propanediyl dinitrate (16) showed a melting point of 58 °C and DSC onset/peak of 177/188 °C. 

The ring opening of 2,2 -diphenyloxetane has been achieved using cerium(iv) ammonium nitrate (CAN) as a redox catalyst (Equation 7) <2003TL4585>. The first step involves oxidation of the oxetane by Ce(rv) to a cyclic radical cation. Equilibration to the ring-opened distonic version 42 with a stabilized cation, then quenching of the cation with methanol and reduction of the alkoxide radical by Ce(lll) to the anion, completes the catalytic cycle. 

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