1 ,3-Dipolarcycloaddition 2 1 ,3-dipolar cycloadditions 2 3 formylpyridine 2 Amino acids 2 Cycloaddition 2 Cycloaddition reaction 2 Diastereo-selectivity 2 Dipolar cycloadditions Optimized conditions 2 Stereochemistry 2 Stereogenic centers 2 Stereoselectivity 2 Stereospecific synthesis 2 alanine 2 aldehyde 2 anisaldehyde 2 arabinose 2 article 2 azomethine ylide 2 benzaldehyde 2 carbon 2 chemical structure 2 cycloaddition 2 dipole 2 ester 2 glycine 2 isomerization 2 ketone derivative 2 nitrogen 2 pentose 2