ASYMMETRIC-SYNTHESIS OF A PROTECTED PHOSPHONATE ISOSTERE OF PHOSPHOTHREONINE FOR SOLID-PHASE PEPTIDE-SYNTHESIS

The first enantiospecific synthesis of 2, a phosphonate isostere of ph osphothreonine suitably protected for solid-phase peptide synthesis, h as been achieved by coupling the highly face-selective conjugate addit ion of the lithium salt of Schollkopf's bislactim ether to E-prop-2-en yl-phosphonates with a selective enzymatic carboxylic ester hydrolysis . The absolute configuration of the products has been assigned from th e X-ray structure of the adduct 9c.