Oxetanes cleavage, lithium aluminum hydride

Reduction of oxetanes can usually be achieved with lithium aluminum hydride in THF. The reaction is almost general, though polyalkyl substitution may decrease the rate to an impractical level. As is to be expected with a strong nucleophile, ring cleavage occurs generally between the oxygen atom and the least substituted a-carbon atom (equation 46)... 

A similar approach to branched-chain aldonolactone sugars has been recently reported by Mattay." Lithium aluminum hydride reduction of photoproduct (36) afforded the desired alcohol which rearranged under acidic conditions to the deoxygenated apiose derivative (38). This process is notable since such reductions usually proceed with cleavage of the oxetane moiety. Also noteworthy are the rapid assemblage of highly oxygenated functionality and the ease of the synthetic procedure. 

Other impressive results have been reported, for example, mfo-5-acylnorbornene 14 undergoes intramolecular cycloadditions to give polycyclic oxetanes 1562-65. Interestingly, the quantum yield of cyclization is favored by increasing bulk of the substituent. Reductive cleavage by lithium aluminum hydride occurs selectively to allow the synthesis of tricyclic alcohols 16. 

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