The Use of Chiral Auxiliaries Prepared from (-)-β-Pinene in Stereoselective Reduction of β-Ketobutyrates
摘要:
Chiral auxiliaries previously prepared from (-)-beta-pinene (3), alcohols 5a-e and 6, were transformed into beta-ketobutyrates 7a-e and 8 respectively. These compounds were stereoselectively reduced by NaBH4 in the presence of additives (MnCl2 or CaCl2), leading to the corresponding beta-hydroxy butyrates 10a-e and 11 in good chemical yield and poor to moderate stereoselectivities (de 0%-60%). The configuration at the newly generated stereogenic center in 10a was determined to be S through its transformation into S-(+)-butanediol.
Synthesis and structural determination of new chiral auxiliaries derived from (−)-β-pinene
摘要:
New chiral auxiliaries, alcohols syn-11a,e and syn-12a,e, were readily synthesized in a stereoselective manner from (-)-beta-pinene. Their stereochemical determinations have been made on the basis of nOe experiments. (C) 1997 Elsevier Science Ltd.