合成路线1

The intermediate (XLI) has been obtained as follows: The condensation of the silylated propionic aldehyde (I) with the chiral allene (XXIII) by means of BF3/Et2O gives the acetylenic alcohol (XXIV), which is desilylated with TBAF, yielding the diol (XXV). The reaction of (XXV) with p-methoxybenzaldehyde dimethyl acetal (XXVI) affords the cyclic ketal (XXVII), which is treated with Red-Al to provided the primary alcohol (XXVIII). The asymmetric Sharpless epoxidation of the double bond of (XXVIII) gives the epoxide (XXIX), which is methylated with Me2CuCNLi2, yielding the chiral diol (XXX). The regioselective acylation of (XXX) with pivaloyl chloride affords the monopivalate (XXXI), which is silylated with Tes-Otf, providing the silyl ether (XXXII). The reductive cleavage of the pivalate ester of (XXXII) with Red-Al furnishes the primary alcohol (XXXIII), which is oxidized with DMP to the aldehyde (XXXIV). The condensation of (XXXIV) with the bromoallyl compound (XXXV) gives the homoallyl alcohol (XXXVI), which is treated with NaH in THF to afford the conjugated diene (XXXVII) (2). The reductive cleavage of the cyclic ketal group of (XXXVII) with iBu2AlH gives the primary alcohol (XXXVIII), which is treated with I2 and PPh3 to yield the iodo derivative (XXXIX). Finally, this compound is condensed with 9-methoxy-9-borabicyclo[3,3,1]nonane (XL) by means of BuLi in THF/ethyl ether to furnish the desired intermediate, the lithium salt (XLI).