Oxido compounds aldehydes

Aldehydes from glycol monoethers and oxido compounds... 

Tetraethylammonium bromide Reactions of oxido compounds catalyzed by quaternary ammonium salts 1,3-Dioxolanes from aldehydes... 

The reaction of 2-lithio-l,3-dithianes with oxido compounds has been used for the stereospecific substitution of steroids both epimers could be obtained via this route Syntheses through dihydro-1,3-oxa-zines, originally used for the preparation of various aldehydes have been extended to ketones and acids difficult to obtain otherwise. 

Degradation of oxido compounds via aldehydes with loss of 1 C-atom... 

Aldehydes from oxido compounds Oxidative cleavage... 

Dicobalt octacarbonyl dissolved in isopropanol, propylene oxide added under Ng when GO-evolution has ceased, cooled if the reaction becomes too vigorous after 15-20 min., and the mixture distilled after ca. 1 hr. -v acetone. Y 75%.— This method gives ketones whereas aldehydes are usually obtained from 1,2-oxido compounds. F. e. s. J. L. Eisenmann, J. Org. Ghem. 27, 2706 (1962). 

Aldehydes from oxido compounds with rearrangement... 

A one-carbon homologation of carbonyl compounds is an important and extensively used method for the preparation of desired carbonyl compounds . One-carbon ring-expansion or one-carbon homologation of ketones or aldehydes via a S-oxido car-benoid is a representative example of the homologation, but few methods have been reported . 

L-Phenylalanine,which is derived via the shikimic acid pathway,is an important precursor for aromatic aroma components. This amino acid can be transformed into phe-nylpyruvate by transamination and by subsequent decarboxylation to 2-phenylacetyl-CoA in an analogous reaction as discussed for leucine and valine. 2-Phenylacetyl-CoA is converted into esters of a variety of alcohols or reduced to 2-phenylethanol and transformed into 2-phenyl-ethyl esters. The end products of phenylalanine catabolism are fumaric acid and acetoacetate which are further metabolized by the TCA-cycle. Phenylalanine ammonia lyase converts the amino acid into cinnamic acid, the key intermediate of phenylpropanoid metabolism. By a series of enzymes (cinnamate-4-hydroxylase, p-coumarate 3-hydroxylase, catechol O-methyltransferase and ferulate 5-hydroxylase) cinnamic acid is transformed into p-couma-ric-, caffeic-, ferulic-, 5-hydroxyferulic- and sinapic acids,which act as precursors for flavor components and are important intermediates in the biosynthesis of fla-vonoides, lignins, etc. Reduction of cinnamic acids to aldehydes and alcohols by cinnamoyl-CoA NADPH-oxido-reductase and cinnamoyl-alcohol-dehydrogenase form important flavor compounds such as cinnamic aldehyde, cin-namyl alcohol and esters. Further reduction of cinnamyl alcohols lead to propenyl- and allylphenols such as... 

For the preparation of an acetal, the carbonyl compound is generally used directly. However, where the aldehyde is rather volatile, a polymeric form is preferred. For example, the trimer, paraldehyde, is often used instead of acetaldehyde. In other cases, the carbonyl compound has been used as its diethyl or dimethyl acetal. It has been found that, whereas the paraldehyde-sulfuric acid reagent often yields the seven-membered, oxido-diethylidene ring (2), 1,1-dimethoxyethane or 1, l-diethoxyethane, and an acid catalyst, afford only the six-membered, ethylidene ring. 

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