Abstract: A method for esterification of one or more carboxylic acid groups in a compound containing one or more carboxylic acid groups wherein the esterification reagent is a diazo-compound of formula: wherein the R1 and R2 groups of the diazo compound are selected such that the corresponding organic compound of formula: exhibits a —C—H pKa value between 18 and 29 as measured in DMSO. Specific reagents and methods for esterification are provided. The esterification reagents provided exhibit high selectivity for esterification of carboxylic acid groups over reaction with amine, alcohol or thiol groups in the compound containing one or more carboxylic acid groups. The method can be used to selectively esterify carboxylic acid groups in peptides or proteins.

Abstract: A user calls a directory assistance service provider to search for a desired telephone number and be connected to a party at the desired number. In one such connection, the user is afforded enhanced directory assistance upon a user command in the form of an out-of-band signaling message, e.g., SS7 signaling message. For example, the user may be afforded further operator assistance by pressing on the user telephone a predetermined key (e.g., “*” key), which is detectable by the directory assistance service provider as an SS7 signaling message.