A Harvard research group, collaborating with chemists around the world, has successfully synthesized vitamin B-12, the only vitamin that has not been previously reproduced.

This breakthrough in organic chemistry is the result of an 11-year research program jointly undertaken by Harvard and Switzerland's Federal Institute of Technology in Zurich. Ninety-nine scientists from 19 countries have participated in the program.

Vitamin B-12 is used in the treatment of pernicious amenia. Plans to synthesize the vitamin for medical use are not underway however, because natural B-12 is a fairly cheap by-product of certain chemical processes.

Robert B. Woodward, Donner Professor of Science, who headed the Harvard contingent, said that the success will have few immediate results, but it is possible that this breakthrough will lead to the discovery of synthetic compounds superior to their natural counterparts. "Natural materials are not always the best," he said.

More important than the actual synthesis of vitamin B-12 were the chemical principles developed during the investigation, Woodward said. Woodward and Ronald Hoffman of Cornell found new rules of "orbital symmetry" in organic compounds.

Professor Woodward was awarded a Nobel Prize in 1965 for his "new and daring philosophies of organic synthesis."