Synthesis of a novel spiro-phosphino-oxazine ligand and its application to Pd-catalyzed asymmetric allylic alkylation
摘要:
Spiro-phosphino-oxazine (+)-8 is prepared from the amino alcohol (+)-5 in two steps with an isolated yield of 90%. When used as a ligand in the Pd-catalyzed alkylation of 1,3-diphenylallyl acetate with dimethyl malonate, products having enantiomeric excesses up to 91% were obtained. (C) 2003 Elsevier Ltd. All rights reserved.
Synthesis of a 1,3-spiro-amino-alcohol-derived chiral auxiliary and its application to Diels–Alder reactions
摘要:
A short synthesis and resolution of (1R,5R,6R)-6-aminospiro[4.4]nonan-2-ol, 11, is reported. The pivalamide derivative (+)-5 gives excellent diastereo- and regiocontrol as well as endo selectivity as a chiral auxiliary in the BCl3-catalyzed Diels-Alder reaction with a variety of symmetrical and unsymmetrical dienes. The adducts are readily cleaved by saponification, allowing recovery and reuse of (+)-5. (C) 2003 Elsevier Science Ltd. All rights reserved.