Lithium aluminium hydride reaction with unsaturated ketones

Instead to acid fluorides the reaction between trifluorovinyllithium and carbonyl compounds can lead to oc-fluoro-oc,0-unsaturated aldehydes and ketones by treating the intermediate lithium alkoholates either with a lithiumalkyl or lithium aluminium hydride, as the geminal fluoro atoms on the vinylic carbon in the alcoholates are susceptable to nucleophilic replacement by these reagents (reaction sequence (51)). Finally, rearrangement yields the a-fluoro-a,(J-unsaturated aldehydes and ketones 55). 

Starting with (54), the hydroxy-group was removed by mesylation and subsequent reduction with lithium aluminium hydride. The resulting compound (55) was converted into the pentacyclic methyl ether (56) using the analogous reaction sequence employed for the previously described synthesis of (52). Birch reduction of (56) and reacetylation yielded the enol ether (57). This compound was hydrolysed with dilute oxalic acid to the unsaturated ketone (58). Reduction with sodium borohydride followed by mesylation and treatment... 

The sensitized photo-oxygenation of 5-methylene-4,7,7-trimethylcyclohepta-l,3-diene was found to give a mixture of the peroxide (233 36 %) and two aP-unsaturated ketones that were not identified (ketone yields = 3.5 % and 1 %). Several reactions of the peroxide (233) were studied, including thermal and photochemical conversion into the syn-bis-epoxide and the potassium hydroxide-methanol conversion into the hydroxyketone (234 X = O), which exists in equilibrium with its bicyclic hemi-ketal form. Lithium aluminium hydride reduction of peroxide (233) gave a mixture of the epimeric alcohols (234 X = H or OH). ... 

The thioenol ethers are stable towards base and lithium aluminium hydride -but are reconverted to the parent compound on dilute acid hydrolysis. Raney nickel desulphurization can be used to form the diene . Hydrogen peroxide oxidation will convert the acid-labile thioenol ether to an acid-stable sulphoxidoenol ether . The sulphoxidoenol ether may be desulphurized with Raney nickel to the diene, or with lithium aluminium hydride reconverted to the thioenol ether for hydrolysis to the (x,j3-unsaturated ketone . These reactions are depicted in equation (80). 

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