Chiral Synthesis via Organoboranes. 13. A Highly Diastereoselective and Enantioselective Addition of diisopinocampheylboranes to Aldehydes

Article abstract of DOI:10.1021/ja00213a029

Isomerically pure <(Z)-γ-methoxyallyl>diisopinocampheylboranes <1, prepared from (+)-α-pinene; 2, prepared from (-)-α-pinene> have been prepared from B-methoxydiisopinocampheylborane and lithiated allyl methyl ether.These enantiomeric <(Z-γ-methoxyallyl>diisopinocamphpeylboranes, the first such derivatives to be synthesized, retain their stereochemical identity under the reaction conditions.They have been succesfully condensed with various aldehydes, such as acetaldehyde, propionaldehyde, 2-methylpropionaldehyde, and benzaldehyde in a regioselective and stereoselective manner to yield the corresponding threo-β-methoxyhomoallyl alcohols in >/= 99percent diastereoselectivities and >/= 95percent enantioselectivities.Similarly, <(Z)-γ-(methoxymethoxy)allyl>diisocampheylborane (3) was prepared and was utilized for the preparation of threo-1,2-diol.