Patent ID: 7312335

Claim:
A compound represented by formula I: wherein, independently for each occurrence: R represents a substituted or unsubstituted alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heteroaralkyl, heterocyclic, or heterocycloalkyl; R 1 represents a substituted or unsubstituted alkyl or alkenyl; R 2 and R 3 represent alkyl, alkenyl, aryl, cycloalkyl, aralkyl, heteroalkyl, halogen, hydroxy, cyano, amino, acyl, alkoxyl, silyloxy, amino, nitro, thiol, amine, imine, amide, phosphonate, phosphine, carbonyl, carboxyl, silyl, ether, thioether, sulfonyl, selenoether, ketone, aldehyde, or ester; n is an integer from 0 to 5 inclusive; m is an integer from 0 to 8 inclusive; and R 4 represents —OH, —OTf, —ONf, —SH, —NH 2 , —NHR 2 —NH(C═O)NR 2 R 3 , —NH(SO 2 )R 2 , —NH(C═O)OR 2 , or —NH(C═O)R 2 .