Diastereocontrolled Synthesis of Optically Pure Functionalized Heterohelicenes

Article abstract of DOI:10.1016/S0957-4166(00)80425-5

(1R,2S,3R,4S)-exo-3-Amino-exo-2-hydroxyborane (exo-amino alcohol) and (1R,2R,3S,4S)-endo-3-amino-endo-2-hydroxybornane (endo-amino alcohol) were found to be efficient diastereomeric chiral auxiliaries for the preparation of functionalized optically pure heterohelicenes.The diastereoselectivities in the synthesis of the helicenes via photocyclization were controlled by the use of these chiral auxiliaries and the resulting diastereomers were readily separated by column chromatography.Removal of the chiral auxiliaries gave optically pure (+)-(P)- and (-)-(M)-<7>heterohelicenes, whose rotational values were +2830 and -2770 respectively.