Two-Directional Elaboration of Hydroxyacetone under Thermodynamically Controlled Conditions:  Allylation or 2-Propynylation and Aldol Reaction

Teruhiko Ishikawa,* Toshiaki Aikawa, Eiko Ohata, Takako Iseki, Satoshi Maeda, Takashi Matsuo, Tatsuo Fujino, and Seiki Saito*
Department of Medical and Bioengineering Science, Graduate School of Natural Science and Technology; Okayama University, Tsushima, Okayama, Japan 700-8530
J. Org. Chem., 2007, 72 (2), pp 435–441
DOI: 10.1021/jo0618573
Publication Date (Web): December 15, 2006
Copyright © 2007 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, seisaito@biotech.okayama-u.ac.jp

Abstract

Abstract Image

Enolate generated from O-(tetrahydropyran-2-yl)hydroxyacetone under thermodynamically controlled conditions (1.3 equiv of NaH, THF, 0 °C to rt) was allylated at the carbon bearing the protected hydroxy group with very high regioselectively. When tert-BuOH, equivalent to the excessive portion of initially added NaH, was introduced into the mixture followed by addition of aldehyde, aldol reaction took place on the methyl group to give 1-substituted 4-hydroxy-(1E),6-heptadien-3-one in acceptable yields after acidic treatment of the mixture for dehydration and deprotection. Introducing a chiral auxiliary protecting group 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 generated under thermodynamically controlled conditions has opened a new avenue for two-directional elaboration of hydroxyacetone that should be potentially useful in organic synthesis.

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History

  • Published In Issue January 19, 2007
  • Received September 7, 2006

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