Epoxy esters from unsaturated ketones

In a most interesting paper, another group led by Trost has described a stereoselective route to unsaturated esters from a,/S-epoxy-ketones by spiro-annelation followed by Grob-type rrans-coplanar fragmentation. The overall idea is outlined for one example in Scheme 46. ... 

When epoxy ester 35 was subjected to these reaction conditions, acetal 36 was formed as a single diastereomer [55]. Hydrolysis of the acetal afforded an enone, thus the net transformation represented a new conversion of an ester into an a,jS-unsaturated ketone. Wipf and Methot used this reaction in a synthesis of pyridazinones [56] (Scheme 9). The optimized conditions included addition of 5 mol% of triphenyl phosphite to the reaction mixture and adsorbing AgCl04 onto Celite to improve the stability and simplify the handling of the reagent. Conjugate addition to 36 followed by hydrolysis formed enone 37. A second cuprate addition, followed by cyclization using hydrazine and subsequent oxidation afforded pyridazinone 38 in 86% yield from 36. 

Two resins were used to do the first study on laminate construction. The first was a brominated epoxy vinyl ester resin with antimony pentoxide and the second was a brominated unsaturated polyester resin. They were both promoted to cure at room temperature with methyl ethyl ketone peroxide catalyst. The panels were then postcured at 250°F (121°C) for 8 h. Panels were prepared that varied in glass content from 25% to 70% and panel thickness varying from 0.05 in. to 0.25 in. and were tested at the same testing facility. A summary of the FSI test data for the first set of panels tested are shown in Figures 23.1 and 23.2. This graph in Figure 23.1 plots the FSI value versus the panel thickness. This data would indicate that the thickness of the test panel has no effect on the measured... 

Lower valent tungsten halides are a new class of deoxygenation agents, e.g. for the conversion of carbonyl or epoxy compounds into olefins . A new reagent, generated in situ from iron pentacarbonyl and a small amount of base in moist solvents, selectively and efficiently hydrogenates the ethylenic portion of a,/ -unsaturated carbonyl compounds, such as ketones or lactones, under mild conditions. Aliphatic tert. amides can be easily reduced to alcohols by alkali metals in hexa-methylphosphoramide and a protic cosolvent such as tert-butanol. Aldehydes can be obtained from acids by catalytic reduction of intermediate carboxylic alkoxyformic anhydrides . Sec. nitro compds. are converted into ketones by the joint action of a nitrite ester and NaNOg under mild, non-acidic conditions . 

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