L-Valine → N-(tert-Butoxycarbonyl)-L-valyl-L-valine

Participants

Reaction Steps

Boc-Val-OSu (12.6 g, 40 mmol) and H-Val-OH (4.68 g, 40 mmol) were condensed in DMF (250 ml) for 96 hours in the presence of 2 ml Et3N. More Et3N was added when needed to maintain the reaction slightly basic. The remaining insoluble material was filtered off and the filtrate evaporated to dryness (45°). The residue was partitioned between ether and dilute H2SO4 (~1%) and the organic layer washed with water (3×), dried over Na2SO4 and evaporated to a foamy glass. The product was crystallized from ether and petroleum ether: Yield, 12.2 g (96.4 %); mp 155°-158°; [α]D25 = +1.10° (c 1, DMF.

Provenance & Evidence