Chemists have devised a much easier way, they say, to make the world's most widely prescribed birth control pill. The efficient synthesis, reported in last week's Journal of the American Chemical Society, could improve access to the oral contraceptives in developing countries.
Each year, women around the world buy hundreds of millions of dollars worth of desogestrel, a contraceptive made in the Netherlands. Synthesizing desogestrel is no simple task, as the small steroid is crammed with stereocenters--carbons bonded to four different groups, one of the most difficult arrangements of atoms to manipulate. The convoluted, 24-step synthesis is also expensive, because it begins with a compound extracted and purified from rare Mexican yams.
Looking for a cheaper alternative, chemists at Harvard University started with a readily available compound containing two rings, leaving only two more to be constructed. After 4 years and four failed attempts, E.J. Corey and Alan Huang found a way to turn their starting material into desogestrel. The new recipe requires just 14 steps to put together the molecule, using various tricks of the trade to build the six stereocenters. The new synthesis yields more than three times as much desogestrel as the standard route, Huang says.
The researchers decided not to patent the synthesis, instead making it freely available to companies that may want to produce a cheaper birth control pill. Lower cost should also allow countries and charitable organizations to donate more pills or sell them at a lower price, says Shanti Conly, director of policy research at Population Action International, in New York.