Ketones, reaction with DIBAL

Scheme 1.20. Double Michael-type addition of dienolate 220 to Cgo, affording after workup the thermodynamically more stable Irans-disubstiluted ketone ( )-219. Due to steric congestion, the corresponding civ-adduct is not available through Diels-Alder reaction with the silyl enol ether corresponding to 220. Reduction of the racemic ketone ( )-219 with DIBAL-H diastereoselec-tively affords alcohol ( )-223.

The P-hydroxy thioester products may be transformed to 1,3-diols by LiAlH4 reduction. Protection of the hydroxyl group followed by reaction with DIBAL-H leads to the corresponding P-alkoxy aldehydes.Alternatively, treatment with a cuprate reagent produces the corresponding ketone. ... 

The Peterson reaction of the chlorovinyl-complex with ethyl trimethylsilylacetate provided the 11Z isomer preferentially (77%), and the 1 IE isomer as a secondary product (15%). The ester was transformed into the C 8 ketone (PhsSnCfy, BuLi, Et20, 79%). Reaction with (/Pr0)2P(0)CH2CN afforded the 1 lZ-retinonitrile in 73% yield. The complex was removed by CuC (72%) and DIBAL-H reduction led quantitatively to 1 lZ-retinal, Fig. (24). 

Newly added reactions are DIBAL-H reduction of esters, and dialkylcuprate reaction with acid chlorides to produce ketones. 

The F-alkyl ketone enolates were readily prepared by dephosphorylation of the corresponding 1-substituted F-l-aUcenyl phosphates with DIBAL at 0°C for a few minutes (Scheme 6.29) [50]. The resulting diisobutylaluminum enolate undergoes aldol reaction with benzaldehyde to give fhe -hydroxycarbonyl compound in a reasonable yield. 

When used in combination with TBHP, DIBAL can promote the oxidation of alcohols into the corresponding ketones via an Oppenauer type reaction with the TBHP being reduced by the aluminum alkoxide (eq 39). In the case of allylic alcohols, this combination affords the epoxidation products (eq 40). ... 

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