New Prostacyclin Analogues

Abstract

According to preliminary kinetic measurements the rate of hydrogenation is nearly proportional to the concentration of chromium or titanium catalyst and corresponds to a reaction of first order referred to magnesium [']. In the case of the chromium catalyst (0.086 mol Cr/l) the rate of hydrogenation increases only slightly with increasing hydrogen pressure between 5 and 80 bar.The following experimentally verified reactions may be regarded as possible steps of the homogeneously catalyzed hydrogenation of magnesium: (i) metallic magnesium reacts with anthracene in THF at 20°C or above in the molar ratio 1 : 1 to give orange, sparingly soluble anthracenemagnesium (2) [eq. (a)]; (ii) in the reaction of (2) with CrC& or TiC1, in THF, which leads to formation of the catalytically active species, free anthracene (1)

(±)-4-Oxo-9-deoxy-9-azaprostaglandin I2 derivatives. Very stable prostacyclin analogs

“…One such compound (3, R1 = Ac, R~ = OTHP) had already been synthesized by Bartmann et al (12) in seven steps from the Corey lactone 4 (13). In our hands, I~ontribution No.…”

Studies related to maytansinoids

“…The desired product (23) was obtained, but in reduced yield because of the facile loss of the silyl protecting group during work up which gave a more polar product, probably compound (24). The latter was spontaneously transformed with time to a non-polar material, possibly compound (25).…”

“…triethylamine (0.218 g, 3.15 mmol), t-butyldimethylsilyl chloride (0.38 g, 2.5 mmol), and finally a catalytic quantity of 4-dimethy1amin0pyridine.l~ s, SiMe,), 0.88 (9 H, s, SiCMe,), 2 25. (2 H, t, J 6 Hz, 5-CH), 2.47 (2 H, d, J 5 Hz), 3-CH2), 3.07 (3 H , s, MeSO,), 3.33 (4 H, s, 5-CH2), 3.85 (2 H, t , J 6 Hz, 6-CH,), 4.56 (2 H , Abq, J 6, 4 and 12 Hz, 1-CH,).…”