620609-64-5Relevant academic research and scientific papers
Straightforward synthesis of derivatives of D- and L-galactonic acids as precursors of stereoregular polymers
Romero Zaliz, Carmen L.,Varela, Oscar
, p. 2579 - 2586 (2003)
High yielding routes for the synthesis of selectively protected derivatives of D- and L-galactonic acids, having free OH or NH2 groups at the C-6 position, are reported. The successful direct per-O-methylation of galactonic acid derivatives from the corresponding galactono-1,4-lactones was developed as a key step of the sequence. For example, 6-azido-6-deoxy-L-galactono-1,4-lactone 16 was converted into the potassium salt and methylated (NaH, DMSO, MeI) to the methyl ester of the 2,3,4,5-tetra-O-methyl derivative 12. Compound 16 was readily prepared by bromination at C-6 of L-galactonolactone 1 and isopropylidenation; followed by substitution of bromine by azide and removal of the protecting groups. Hydrolysis of the methyl ester of 12 and hydrogenation of the azide led to the tetra-O-methyl derivative of the 6-amino acid 18 with 52% overall yield from 1. The same sequence applied to D-galactonolactone 19 led to the enantiomeric amino acid 25 with a 47% overall yield.
