Diastereoselective Allylations of Allyl−Propargyl Hybrid Cations: Synthesis of Conjugated 1,5-Dien-7-yne Frameworks Bearing C(4)-Stereogenic Centers
摘要:
Chiral C(4)-substituted (E)- or (Z)-1-alkynyl-1-trimethylsilyloxy-2-butene systems provide anti-(Z) or syn-(Z) conjugated dienyne, with a very high level of stereocontrol, on treatment with (BF3OEt2)-O-. in CH2Cl2 at -50 degreesC in the presence of allyltrimethylsilane. The Cieplak conformation for (E)-substrates and neighboring-group participation for (2)-substrates are considered to be responsible for the stereochemical consequences.
Diastereoselective Allylations of Allyl−Propargyl Hybrid Cations: Synthesis of Conjugated 1,5-Dien-7-yne Frameworks Bearing C(4)-Stereogenic Centers
摘要:
Chiral C(4)-substituted (E)- or (Z)-1-alkynyl-1-trimethylsilyloxy-2-butene systems provide anti-(Z) or syn-(Z) conjugated dienyne, with a very high level of stereocontrol, on treatment with (BF3OEt2)-O-. in CH2Cl2 at -50 degreesC in the presence of allyltrimethylsilane. The Cieplak conformation for (E)-substrates and neighboring-group participation for (2)-substrates are considered to be responsible for the stereochemical consequences.