Efficient Synthetic Method for l-Tartaramides by Aminolysis of Reactive 2,3-O-Isopropylidene-L-tartaryl Chloride

Abstract

The reactive 2,3-O-isopropylidene-L-tartaryl chloride 4 was firstly synthesized from L-(+)-tartaric acid. Various chiral 2,3-O-isopropylidene-L-tartaramides 5 were prepared by aminolysis of the reactive L-tartaryl chloride 4 with primary and secondary amines.

Notes

To characterize bis(trimethylsilyl) 2,3-O-isopropylidene-L-tartrate 3, when the dried oily product 3 was subject to distill under high vacuum at elevated temperature, it become sponge-like solid material. However, when this solid material under nitrogen was treated as above with oxalyl chloride, L-tartaryl chloride 4 was obtained.

The IR spectrum of 2,3-O-isopropylidene-L-tartaryl chloride 4 was varied in significant when measuring in neat. When the absorption peaks at 1799 and 1740 cm⁻¹ was disappearing, and the new peaks at 1808 and 1721 cm⁻¹ was appearing. Apparently, The acid dichloride 4 was partially hydrolyzed and turns to acid anhydride, 2,3-O-isopropylidene-L-tartaric anhydride; IR (neat) 2993 w, 2963m, 1808 s, 1721 vs, 1260 s, 1226 m, 1091 s, 1017 s, 800 s cm⁻¹.