合成路线1

The condensation of 4(R)-phenyloxazolidin-2-one (I) with 2(E)-pentenoyl chloride (II) by means of BuLi in THF gives 3-[2(E)-pentenoyl]-3(R)-phenyloxazolidin-2-one (III), which is treated with 3-[bis(trimethylsilyl)amino]phenylmagnesium bromide (IV) and CuBr in DMSO/THF regioselectively yielding the addition product (V). Elimination of the silyl groups of (VII) in mild acidic conditions and treatment of the resulting amine with benzyl bromide affords the dibenzylated amine derivative (VI), which is regioselectively acylated with 2-methoxy-2-methyl-1,3-dioxolane (V) and TiCl4 in dichloromethane under basic conditions giving the dione (VIII). The condensation of (VIII) with 1-phenyl-3-hexanone (IX) by means of Ti(OBu)Cl3 in dichloromethane as before yields the hydroxy-dione (X), which is cyclized by means of potassium tert-butoxide in THF to afford the dihydropyrone (XI). The debenzylation of (XI) by hydrogenation with H2 over Pd/C in methanol/ethyl acetate gives the free amine (XII), which is finally sulfonated with 5-(trifluoromethyl)pyridine-2-sulfonyl chloride (XIII) in pyridine/dichloromethane

合成路线2

1) The condensation of 1-phenylhexan-3-one (I) with ethyl acetate by means of butyllithium and diisopropylamine in THF gives racemic 3-hydroxy-3-(2-phenylethyl)hexanoic acid ethyl ester (II), which is hydrolyzed with NaOH in methanol to the corresponding free acid (III). The optical resolution of (III) with (1R,2S)-(-)-norephedrine (IV) followed by treatment with aqueous HCl yields the chiral (R)-acid (V), which is treated with 4-biphenylyloxymethyl chloride (VI) and diisopropylethylamine in toluene affording the protected ester (VII). The reduction of the ester group of (VII) with diisobutylaluminum hydride (DIBAL) in toluene gives the monoprotected diol (VIII), which is oxidized at the primary hydroxy group with 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy radical (TEMPO) and NaOCl yielding the corresponding aldehyde (IX). The condensation of (IX) with (R)-3-(3-nitrophenyl)pentanoic acid methyl ester (X) by means of sodium hexamethyldisilazide (NaHMDS) in THF gives the hydroxyester (XI) as a mixture of four diastereomers. This mixture is oxidized with pyridinium chlorochromate (PCC) in dichloromethane to afford the ketoester (XII) also as a mixture of two diastereomers. Elimination of the biphenylyloxymethyl protecting group with H2SO4 in methanol yields the hydroxy ketoester (XIII).

合成路线3

A new synthesis of PNU-140690 has been developed: The condensation of 1-phenyl-3-hexanone (I) with methyl acetoacetate (II) by means of NaH in THF, followed by cyclization gives the hydroxypyrone (III), which by condensation with 3-nitrobenzaldehyde (IV) by means of AlCl3 in THF yields the benzylidene-pyrone (V). The alkylation of (V) with Et3Al, CuBr-Me2S in THF affords intermediate (VI), which is reduced at the nitro group with H2 over Pd/C in methanol giving the racemic amine (VII). The optical resolution of the N-benzyloxycarbonyl derivative of (VII) with chiral HPLC yielded the desired (R,R)-enantiomer (VIII), which was finally sulfonated with 5-(trifluoromethyl)pyridine-2-sulfonyl chloride (IX) in pyridine/dichloromethane.

合成路线4

合成路线5