OPTICALLY ACTIVE DIAZO COMPOUNDS. II

How nucleophilic are diazo compounds?

The kinetics of the reactions of benzhydryl cations with eight diazo compounds 1 a-g were investigated photometrically in dichloromethane. The nucleophilicity parameters N and slope parameters s of these diazo compounds were derived from the equation log k (20 degrees C)=s (E+N) and compared with the nucleophilicities of other pi systems (alkenes, arenes, silyl enol ethers, silyl ketene acetals...

Optically Active Coordination Compounds. Part 50.' 4-Fold Symmetry Axes in Optically Active Complex Ions from Natural Nicotine

Diazo Compounds: Versatile Tools for Chemical Biology.

Diazo groups have broad and tunable reactivity. That and other attributes endow diazo compounds with the potential to be valuable reagents for chemical biologists. The presence of diazo groups in natural products underscores their metabolic stability and anticipates their utility in a biological context. The chemoselectivity of diazo groups, even in the presence of azido groups, presents many o...

Circula:r Dichroism of Optically Active 1,2-Disubstituted 1,2-Diphenyl Ethanes Part II: Compounds without COOR-group at Benzylic CY

(R,R)-Hydrobenzoin and homochirally analogous thTeo-compounds of formula Ph-CHX-CHY-Ph (X = Y; X rO Y; Y = H) show anegative O-O CD-line below 37200 crn? and/er a positive one just above it, which can be explained by conformational equilibria around the Ph-C bonds. The Cotton effect at 220-210 nm is negative for this same configuration, if X rO Y (also Y = H), in these other cases there no such...

Are lignins optically active?

The accepted derivation of lignins from non(enzymatically)-controlled radical coupling reactions has been recently challenged, and it is relevant to ascertain unequivocally whether lignins are or are not (as normally assumed) optically active. Two approaches were used. First, DFRC (derivatization followed by reductive cleavage) dimers derived from beta-5- and beta-beta-units in pine lignins, wh...