3-alkoxy-4-hydroxy-butenes

Reactions of trichloromethyl-substituted 1,3-dielectrophiles 551 with hydrazine afforded hydroxy pyrazoles 552 (Equation 111) <2002TL5005>. Cyclocondensation of alkenones 553 with phenylhydrazine under microwave irradiation furnished 5-trichloromethyl-substituted pyrazoles 554 in excellent yields (Equation 112) <2003TL6669>. 4-Alkoxy-l,l,l-trichloro-3-alken-2-ones were useful precursors for the regiospecific synthesis of 5-trichloromethylpyr-azoles using hydrazines <2002SC419, 2002SC1585>. l,l,l-Trifluoro-4-ethoxy-3-buten-2-one, 3-trifluoroacetyl-3-buten-... 

Stereoselective addition of a dithiane anion to chiral 2-metiiyl-3-trimethylsUyl-3-butenal combined with the stereoselective addition of a Grignard reagent to the chiral a-alkoxy ketone affords a practical method for the construction of a, y-dimethyl-a,p-dihydroxy compounds, useful intermediates for the synthesis of erythronolides (Scheme 33). -Hydroxy carboxylic esters were synthesized by the addition of ethyl 1,3-dithiolanyl-2-carboxylate enolate to a chiral aldehyde, followed by desulfurization. ... 

Reaction Scheme 7.2 summarizes the reaction mechanism for 1-butene (l-C4Hg) as an example of alkenes. The hydroxyalkyl radicals formed by the pathways (a) and (b) is a kind of alkyl radicals mentioned in the previous Sect. (7.2.2), and exclusively forms hydroxyperoxy radicals by the reaction with O2 in the atmosphere. From the hydroxyperoxy radicals, oxyradicals (hydroxybutoxy radicals) and NO2 (pathways (d), (k)), and partially hydroxybutyl nitrate (pathways (e), (1)) are produced by the reaction with NO as in the case of alkylperoxy radicals described in the previous paragraph. The yields of hydroxylalkyl nitrates are 2-6 % for C4-C6 alkenes (O Brien et al. 1998), which is about half of those for alkyl nitrates from the alkoxy radicals. Hydroxy alkoxy radicals formed in pathways (d) and (k) are known to follow the three reaction pathways, unimolecular decomposition ((g), (n)), H-atom abstraction by O2 ((h), (o)), and dihydroxyl radical formation by isomerization (p), corresponding to reactions (7.25), (7.24) and... 

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