CONJUGATE ADDITION OF LITHIATED SCHOLLKOPF BISLACTIM ETHER TO 1E,3E-BUTADIENYLPHOSPHONATES - STEREOCONTROLLED ACCESS TO 2,3-ANTI-4E 2-AMINO-6-PHOSPHONO-4-HEXENOIC ACID-DERIVATIVES

Face-selective 1,6-addition of lithiated Schollkopf's bislactime ether 5 to 4-substituted, 1,4- or 3,4-disubstituted 1E,3E-butadienylphospho nates 6a-d allows a direct and stereocontrolled access to semi-rigid A P6 analogues, the 2,3-anti-4E 2-amino-6-phosphono-4-hexenoic acid deri vatives 4a-c. The relative stereochemistry was assigned from a NMR stu dy of the cyclic derivative 12c. Ten-membered trans-fused chair-boat-l ike transition states are invoked to rationalize the stereochemical ou tcome of the addition. (C) 1997 Elsevier Science Ltd.