SYNTHESIS OF 3-(TRIETHYLSTANNYL)PROPANOIC ACID - AN ORGANOTIN MASS LABEL FOR DNA

The synthesis of 3-(triethylstannyl)propanoic acid (TESPA), an organom etallic reporter group that enables the mass labeling of oligonucleoti des with stable isotopes of tin, is described. Synthesized from commer cially available isotopically-enriched SnO2 in a five step process, th e NHS ester of TESPA is produced with an overall yield of 40 %. This s implification of the standard synthetic scheme, with two less syntheti c steps and a coincident 60 % yield increase, is accomplished through the use of the reagent N-(acryloxy)succinimide and the free radical in itiator AMPN. The conditions for the attachment of the reporter group to priming oligonucleotides and the subsequent HPLC isolation of the l abeled primers are also detailed.