Cholestenone. The literature method7 was modified by using aluminum isopropoxide in place of aluminum terf-butoxide. A solution of 21 g of freshly distilled aluminum isopropoxide in 130 mL of benzene was added to a solution of 30 g of cholesterol in 350 mL of benzene and 250 mL of acetone. After the mixture was refluxed for 48 h, the product was isolated as described7 to give 18 g of cholestenone, mp 80-81.5 °C (lit.7 mp 78.5-80.5 °C).The filtrate was subjected to recycling which raised the overall yield to 85-90%. 24-Hydroxychol-4-en-3-one Acetate (I). Cholestenone (0.50 g) was dissolved at 0 °C in a solution of 19.5 mL of CF3COOH, 10.5 mL of 96% H2SO4, and 1.0 mL of 50% aqueous H202. After being stirred for 4 h at 0 °C, the solution was quenched by slow addition to ice-water. A hexane extract was washed with 5% NaHC03 and dried over MgS04.After removal of solvent in vacuo at 25 °C, the residue was dissolved in a solution of 50 mL of acetic acid, 2 mL of water, and 1.0 g of sodium acetate. The solution was refluxed for 18 h under N2, cooled, and diluted with 100 mL of water. A hexane extract was washed with 5% Na2C03 and dried over MgS04. Removal of solvent in vacuo at 25 °C gave 0.15 g of crystalline acetate (I). A GC analysis indicated that it was 70% pure with the remainder being unreacted cholestenone.The impure I was chromatographed on 10 g of 28-200 mesh silica gel, using 65:35 hexane-ether. Cholestenone eluted before

The anomeric specificity of Escherichia coli CMP-N-acetylneuraminic acid (CMP-NeuAc) synthetase was investigated by NMR using 13C-labeled N-acetylneuraminic acid (NeuAc). Consumption of the beta-anomer of [2-13C]N-acetylneuraminic acid was observed upon addition of enzyme, with a concomitant appearance of an anomeric resonance for CMP-N-acetylneuraminic acid. Inhibition by substrate analogues the anomeric oxygen was determined in a similar manner using [2-13C,(50 atom %)18O]N-acetylneuraminic acid. An upfield shift of 1.5 Hz in the anomeric resonance of both the [13C]NeuAc substrate and CMP-[13C]NeuAc product was observed due to the 18O substitution. This result implies conservation of the NeuAc oxygen. Results of steady-state kinetic analysis suggest a sequential-type mechanism and therefore no covalent intermediate. Thus, CMP-beta-NeuAc is probably formed by a direct transfer of the anomeric oxygen of beta-NeuAc to the alpha-phosphate of CTP.

Reaction of 2,6-Dimethyl-and 2,4,6-Trimethylpyridine with Trifluoromethanesulfonic Anhydride Summary: The reaction of trifluoromethanesulfonic anhydride with 2,6-dimethyl-and 2,4,6-trimethylpyridine produces compounds in which a methyl hydrogen is replaced by either a trifluoromethyl or a [(trifluoromethyl) sulfinyl]oxy group.

D e p a r t m e n t of C h e m i s t r y C l e v e l a n d S t a t e U n i v e r s i t y C l e v e l a n d , O h i o 44115 TABLE OF CONTENTS I . I n t r o d u c t i o n 11. R e l a t i v e R e a c t i v i t y of Several S u l f o n i c 111. S y n t h e s i s of C a r b o h y d r a t e T r i f l u o r o m e t h -E s t e r s a n e s u l f o n a t e s ( C a r b o h y d r a t e T r i f l a t e s ) 1V. Reactions of C a r b o h y d r a t e T r i f l a t e s A. S u b s t i t u t i o n Reactions 1. F a c t o r s E f f e c t i n g t h e N u c l e o p h i l e 2. I n f l u e n c e of t h e S o l v e n t B. 9 -A l k y l a t i o n Reactions 1. D i s a c c h a r i d e S y n t h e s i s 2 .D e r i v a t i v e F o r m a t i o n C . R e a r r a n g e m e

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