Pyridine, 4-benzoyl bromination with

The treatment of AK/S-D-ribopyranosyl)- and /V-(/3-D-ribofuranosyl)ami-nomethylenemalonates (41 and 42) with benzoyl chloride in pyridine, and then with a 4% solution of bromine in wet chloroform for 24 hr at room temperature, gave tri-0-benzoyl-/3-D-ribofuranosylamine and tri-0-benzoyl-/3-D-ribopyranosylamine hydrobromides (1525 and 1526) in 86 and 84% yields, respectively (88MI1). 

Benzoylation of )V-(2,2-diethoxycarbonylvinyl)-/3-D-galactopyranosy-lamine and -/3-D-gluco analogue in pyridine with benzoyl chloride afforded mixtures of di-, tri-, and tetra-O-benzoyl derivatives. From 2,3,6-tri-O-benzoyl-N-(2,2-ethoxycarbonylvinyl)-j8-D-galatopyranosylamine and -/3-D-glucopyranosylamine the amines were liberated with bromine or chlorine in chloroform or methylene chloride (89MI4). 

A -Benzoyloxypyridinium chloride (72), prepared from pyridine oxide and benzoyl chloride, reacts with silver phenylacetylide selectively at position 2 to afford 2-(phenylethynyl)pyridine (73). The bromine atom of the tetrahydro-l,4-oxazin-2-one 74 is replaced by an alkynyl group on treatment with stannanes 75 (R = hexyl or Ph) the products 76 are transformed into ( S)-amino acids 77 by catalytic hydrogenation. ... 

---