The total synthesis of vitamin B 12 .

The final stages in the total synthesis of vitamin B12 are reported. It was particularly appropriate, I think, and most pleasant for us this morning to see the splendid film provided by our Russian friends, in which the very successful Symposium at Riga was enshrined for posterity. Appropriate in the sense, from my own point of view, that I did report there at Riga, on the progress we had made up until that time, namely, the summer of 1970, in the joint programme, which had as one of its objectives the synthesis of vitamin —a programme carried out collaboratively by myself and Professor Eschenmoser at the Eidgenössische Technische Hochschule in Zurich, with of course our colleagues in Cambridge and Zurich. We have worked very closely and intimately together in this project, and it is an achievement—such as it may be—of the two groups together. So, anything I say this afternoon—or what is left of the morning and this afternoon—I am saying for Professor Eschenmoser and his colleagues as well as for myself and my colleagues in Cambridge.