Two-directional elaboration of hydroxyacetone under thermodynamically controlled conditions: allylation or 2-propynylation and aldol reaction.
Enolate generated from O-(tetrahydropyran-2-yl)hydroxyacetone under thermodynamically controlled conditions (1.3 equiv of NaH, THF, 0 degrees 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.
Ishikawa
Teruhiko
T
Department of Medical and Bioengineering Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama, Japan 700-8530.
Aikawa
Toshiaki
T
Ohata
Eiko
E
Iseki
Takako
T
Maeda
Satoshi
S
Matsuo
Takashi
T
Fujino
Tatsuo
T
Saito
Seiki
S
D000096:Acetone / Q000031:analogs & derivatives* / Q000737:chemistry; D000478:Alkylation; D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D013816:Thermodynamics
D000480:Alkynes; D007659:Ketones; D000096:Acetone; C004433:acetol