Convergent synthesis

In chemistry a convergent synthesis is a strategy that aims to improve the efficiency of multi-step chemical synthesis, most often in organic synthesis. In linear synthesis the overall yield quickly drops with each reaction step:

A → B → C → D

Suppose the yield is 50% for each reaction, the overall yield of D is only 12.5% from A.

In a convergent synthesis

A → B (50%)

C → D (50%)

B + D → E (25%)

the overall yield of E (25%) looks much better. Convergent synthesis is applied in the synthesis of complex molecules (see total synthesis) and involve fragment coupling and independent synthesis.

Examples:

• Convergent synthesis is encountered in dendrimer synthesis ^[1] where branches (with the number of generations preset) are connected to the central core
• Proteins of up to 300 amino acids are produced by a convergent approach using chemical ligation.
• An example of its use in total synthesis is the final step (photochemical [2+2]cycloaddition) towards the compound Biyouyanagin A ^[2]:

See also

• divergent synthesis

References

1. ^ Convergent Synthesis of Internally Branched PAMAM Dendrimers Michael Pittelkow, Jrn B. Christensen Org. Lett., 7 (7), 1295 -1298, 2005
2. ^ Total Synthesis and Revised Structure of Biyouyanagin A K. C. Nicolaou, David Sarlah, and David M. Shaw Angew. Chem. Int. Ed. 2007, 46, 4708 –4711 doi:10.1002/anie.200701552