Chiral pool starting materials, functionalization

Amino acids have been used in ex-chiral-pool syntheses far less frequently. The most popular starting material is serine (available in both configurations), due to the differentiable functional groups at the termini. L-Serine (1) may be converted into a variety of (R)-amino acids 5 by straightforward manipulations12. 

Compounds isolated from natural sources are frequently optically pure. Thus camphor (11), cholesterol (14), morphine (16), for example, are isolated in the optically pure state. The parent molecule of (13) is D-glucose, and like camphor and cholesterol is readily available in very large quantities. These, and comparable compounds, form what is now described as a chiral pool, i.e. low-cost, readily available, chiral compounds which provide starting materials for conversion into other compounds, of simplified skeletal and functional structure, in which some or all of the chiral features have been retained. 

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