Abstract
| - Enolate generated from O-(tetrahydropyran-2-yl)hydroxyacetone under thermodynamically controlledconditions (1.3 equiv of NaH, THF, 0 °C to rt) was allylated at the carbon bearing the protected hydroxygroup with very high regioselectively. When tert-BuOH, equivalent to the excessive portion of initiallyadded NaH, was introduced into the mixture followed by addition of aldehyde, aldol reaction took placeon the methyl group to give 1-substituted 4-hydroxy-(1E),6-heptadien-3-one in acceptable yields afteracidic treatment of the mixture for dehydration and deprotection. Introducing a chiral auxiliary protectinggroup into hydroxyacetone led to asymmetric allylation though stereoselectivity was around 50 % ee.Thus, the hidden aspect of the chemoselective nature of protected hydroxyacetone-derived enolate generatedunder thermodynamically controlled conditions has opened a new avenue for two-directional elaborationof hydroxyacetone that should be potentially useful in organic synthesis.
|