Revisiting [3 + 3] Route to 1,3-Cyclohexanedione Frameworks: Hidden Aspect of Thermodynamically Controlled Enolates
摘要:
We have revisited the traditional consecutive Michael-Claisen [3 + 3] process (MC-[3 + 3]) promising the synthesis of a cyclohexane-1,3-dione derivatives from nonactivated simple ketones and enoates and evaluated its potential in modern organic synthesis. Twenty to thirty examples were demonstrated to be effective. The reactions exhibited remarkable regioselectivity with the Michael addition proceeding through nucleophilic attack by the more hindered site of the ketones without exception. The subsequent Claisen condensation resulted in the formation of carbon-carbon bonds between less hindered site of the ketones and acyl carbon of the enoates. The MC-[3 + 3] process described is useful for the synthesis of Taxol A-ring synthons in multigram quantities and for the synthesis of other six-membered carbocyclic compounds. A number of control experiments have been conducted to provide strong support for the mechanism of this MC-[3 + 3].
Durch basekatalysierte Reaktion zwischen aromatischen Aldehyden und 3‐Methyl‐2‐butanon in wäßrig‐ethanolischer Lösung bei 70° konnten die 5‐Aryl‐3‐isopropyl‐6,6‐dimethyl‐2‐cyclohexenone 4a‐f dargestellt werden. Benzaldehyd und Butanon reagierten analog; zwei der vier möglichen, in schlechter Ausbeute anfallenden 5‐Aryl‐2‐cyclohexenone 6 waren als Oxime zu isolieren.
Durch basekatalysierte Reaktion zwischenarotischen Aldehyden 和 3-Methyl-2-butanon in wäßrig-ethanolischer Lösung bei 70° konnten die 5-Aryl-3-isopropyl-6,6-dimethyl-2-cyclohexenone 4a-f dargestellt werden Benzaldehyd 和 Butanon reagierten 类似物;zwei der vier möglichen, in schlechter Ausbeute anfallenden 5-Aryl-2-cyclohexenone 6waren als Oxime zu isolieren。
UNTERHALT, B.;REINHOLD, H. J., ARCH. PHARM., 1986, 319, N 6, 516-521
作者:UNTERHALT, B.、REINHOLD, H. J.
DOI:——
日期:——
Revisiting [3 + 3] Route to 1,3-Cyclohexanedione Frameworks: Hidden Aspect of Thermodynamically Controlled Enolates
We have revisited the traditional consecutive Michael-Claisen [3 + 3] process (MC-[3 + 3]) promising the synthesis of a cyclohexane-1,3-dione derivatives from nonactivated simple ketones and enoates and evaluated its potential in modern organic synthesis. Twenty to thirty examples were demonstrated to be effective. The reactions exhibited remarkable regioselectivity with the Michael addition proceeding through nucleophilic attack by the more hindered site of the ketones without exception. The subsequent Claisen condensation resulted in the formation of carbon-carbon bonds between less hindered site of the ketones and acyl carbon of the enoates. The MC-[3 + 3] process described is useful for the synthesis of Taxol A-ring synthons in multigram quantities and for the synthesis of other six-membered carbocyclic compounds. A number of control experiments have been conducted to provide strong support for the mechanism of this MC-[3 + 3].