Acyclic alkanone

Reduction.—The differences in stereoselectivity on reduction of several substituted cyclic and acyclic alkanones by hydride reducing agents (interalia LiBBu sH, L1BH4, or LiAlH4) have been documented. The lithium trialkylaluminium hydride (17) has been shown to reduce 4-t-butylcyclohexanone stereoselectively. ... 

In 2000, N eumann and N eimann reported that the treatment of certain ketones with 60% aqueous hydrogen peroxide in HFIP as solvent, and in the absence of further catalysts, results in lactone formation (Scheme 4.13) [21]. After 20h reaction time at 60 °C, good lactone yields were obtained from cydoalkanones. 2-Octanone, as a prototypical acyclic alkanone, reacted sluggishly, whereas no lactone formation was observed for acetophenone (Scheme 4.13). 

The photochemistry of alkanones has been reviewed recently 2c>. It would appear that rate constants for the physical decay processes of both singlets and triplets vary only slightly among a wide collection of structurally varied acyclic, cyclic, and polycyclic alkanones. Consequently, relative triplet yields are determined primarily by relative rates of excited singlet chemical reactions. As in most triplet reactions, overall quantum yields are usually determined primarily by the partitioning of metastable primary photoproducts. 

The dihydroxyacetone reductase of Mucor javanicus is NADPH-dependent, and accepts a wide variety of simple acyclic ketones. For 2-alkanones, hydride attack occurs largely from the Si face with high selectivity to give the (/ )-product. However, butan-2-one was reduced to racemic butan-2-ol, indicating that methyl and ethyl are not differentiated by the enzyme. 

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