合成路线1

In a further method, the lithium acetylide of 2-(propargyloxy)tetrahydropyran (XXXIV) was alkylated with 1-bromo-3-chloropropane (XXXV) to afford chloride (XXXVI). Displacement of the Cl atom of (XXXVI) with NaCN yielded nitrile (XXXVII), which was further hydrolyzed to carboxylic acid (XXXVIII) under basic conditions. Esterification of (XXXVIII) with concomitant tetrahydropyranyl group cleavage in ethanolic H2SO4 gave hydroxy ester (XXXIX). Conversion of (XXXIX) to the corresponding mesylate, followed by treatment with KI, provided ethyl 7-iodo-5-heptynoate (XL). (R)-(+)-nopinone (XXVI) was then alkylated with the propargyl iodide (XL) in the presence of LDA to afford (XLI). Conversion of (XLI) to oxime (XLII), followed by reduction with TiCl3 and BH3•t-BuNH2, provided amino ester (XLIII). Then, partial hydrogenation of the triple bond of (XLIII) over Lindlar catalyst furnished the precursor aminoalkene ester (XLIV).