Hydrogen bond carboxyl-pyridyl

The (E)-alkene (74) is formed from Wittig reaction of the corresponding phenyl 3-pyridyl ketone the stereochemical preference is determined by an interaction (either hydrogen bonding or salt bridging) between the carboxylic acid chain being introduced and the amide tether provided by the reactant." ... 

It has been suggested that the preferential formation of ( )-alkene on Wittig reaction of amide-substituted phenyl 3-pyridyl ketones with non-stabilized phosphorus ylides which contain a carboxyl terminus is a consequence of either hydrogen bonding or salt... 

The well-defined geometric parameters that dictate polymerizations of diacetylenes in the solid state have led Lauher and Fowler to employ principles of supramolecular chemistry to control the reaction within co-crystals. In particular, a urea derivative has been shown to self-assemble to form a hydrogen-bonded 3-array that preorganizes complementary diacetylenes for a 1,4-photopolymerization. Through the use of a derivative with lateral carboxylic acid groups (Scheme 2.3.8(a)) and a bis (4-pyridyl)acetylene as the reactant (Scheme 2.3.8(b)), a solid-state arrangement suitable for the reaction was achieved (Fig. 2.3.11(a)) [58]. Indeed, general applic-... 

---