4-Heptanone aldol reaction

Carbonyl alkylation and condensation reactions are always of great value in synthesis, and the formation of o-ANIS ALDEHYDE via 4,4-dimethyl-2-oxazoline, 2,2-DIMETHYL-3-PHENYLPROPION-ALDEHYDE via alkylation of the magnesio-enamine salt and threo-4-HYDROXY-3-PHENYL-2-HEPTANONE via a directed aldol... 

Wenkert and coworkers have reported several applications of this chemistry to the synthesis of alkaloids and terpenes.110 A recent example, leading to die methyl ether of tetrahydropyrethrolone (97), is illustrated in Scheme 19.116 Reaction of 1,2-dimethoxypropene with 1 -diazo-2-heptanone (98) resulted in the formation of the labile cyclopropane (99), which was directly converted to the 1,4-diketone (100). Base-induced aldol condensation of (100) readily formed (97). Stereoselective syntheses of prostaglandins1 17 and dicranenone A118 have also been developed using acid-induced ring-opening reactions. 

Pentanone is similar to acetone in its behavior, and 1 1 adducts may be obtained from aliphatic aldehydes in good yield (equations 47 and 48). 4-Heptanone and higher symmetrical ketones are much less reactive and give very poor yields of aldols with simple aldehydes. However, the reactions of these ketones with o-phthalaldehyde often provide benzotropone derivatives in excellent yield (e.g. equation 49). Diisopropyl ketone and diisobutyl ketone do not give mixed adducts with aldehydes under tte normal protic conditions. 

Water is removed with especial ease from alcohols whose hydroxyl group is in a /9-position to an oxo, alkoxycarbonyl, nitrile, or nitro group. For example, on aldolization of acetaldehyde the acid present in the reaction medium suffices for dehydration of the product to the unsaturated carbonyl compound, i.e., to crotonaldehyde. One hour s boiling with dilute sulfuric acid suffices for preparation of 3-hepten-2-one from 4-hydroxy-2-heptanone 39... 

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