Practical synthesis of a HIV integrase inhibitor

A practical and efficient synthesis of the potent HIV integrase inhibitor 1 is described. Starting from readily available 3,4-dihydro-2H-pyran, the six-step synthesis features a through process without purification of any of the intermediates until the isolation of crystalline intermediate 7. After deprotection and classical resolution, amine 8 was isolated with excellent enantiopurity. A final amide coupling completed the synthesis of 1 in 7.6% overall yield from DHP. This chromatography-free route is more cost effective and increases the overall yield by nearly 3 times when compared with the original Med Chem synthethic route. This improved chemistry was used successfully to prepare multikilogram quantities of integrase inhibitor 1.