Synthesis of three novel chiral diamines derived from (S

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• 作者：J. Luis Olivares-Romero ; Eusebio Juaristi
• 关键词：Diazaborolidines ; Chiral diamines ; Microwave irradiation ; Organocatalysis ; Asymmetric reduction
• 刊名：Tetrahedron
• 出版年：2008
• 出版时间：13 October 2008
• 年：2008
• 卷：64
• 期：42
• 页码：9992-9998
• 全文大小：521 K

文摘

A series of chiral diazaborolidine catalysts are readily prepared in situ at 75 °C in toluene solvent and under microwave irradiation (100 W, 15 min, air cooling) using chiral diamines derived from inexpensive and commercially available (S)-proline and borane-dimethyl sulfide. Special mention deserves the synthesis of potentially versatile diamine (S)-8 [(S)-(pyrrolidin-2-yl)diphenylmethanamine], with the key step being the conversion of tertiary alcohol (S)-(1-benzylpyrrolidin-2-yl)diphenyl methanol, (S)-12, to azide (S)-13. The chiral diazaborolidine/BH₃ reagent system was successfully employed in the enantioselective reduction of prochiral ketones to give the corresponding secondary alcohols in excellent yield and with up to 96 % enantiomeric purities.