1-Amino-N,N-dibenzyl-1,6-dideoxy-β-L-fructofuranose

Abstract

The title compound, C20H25NO4, the product formed in the Amadori rearrangement of l‐rhamnose with di­benzyl­amine, is shown by X‐ray crystallographic analysis to be a rare example of an Amadori product crystallizing in a furan­ose form.

The Structure of N‐(1‐Deoxy‐β‐D‐fructopyranos‐1‐yl)‐L‐proline Monohydrate (“D‐Fructose‐L‐proline”) and N‐(1,6‐Dideoxy‐α‐L‐fructofuranos‐1‐yl)‐L‐proline (“L‐Rhamnulose‐L‐proline”)

“…The ring bond angles in 2 are significantly, 48 to 98, smaller than respective angles in 1, due to steric constraints in the furanose ring. However, the angle values for 2 compare well, with the exception of the C2-C3-O3 angle, within 38, with respective values in L-rhamnulose-dibenzylamine [35] and the averaged values for furanosides. [40,47] There is also a great deal of similarity in the valence angles for reported proline structures and the amino acid portion of the Amadori compounds 1 and 2 ( Table 3).…”

“…[28,46] The mean values of C-C and C-O bond lengths in the b-D-fructopyranosyl portion of 1 (1.527 Å and 1.424 Å correspondingly) agree well with the corresponding values for b-pyranoses. The 1,6-dideoxy-a-L-fructofuranose in 2 also has no significant deviations in the mean bond distances (1.523 Å and 1.421 Å correspondingly) from those determined for the b-fructopyranose in 1, the b-fructofuranose in L-rhamnulose-dibenzylamine, [35] and the averaged values for furanose structures. [40,47] In the proline part of both 1 and 2, the N1-C7 bond (Table 3) is about 0.04 Å longer than respective bonds in a number of known proline structures, [41,43,45,48] while the rest of the bond lengths compare well.…”

“…[19] In crystalline 2, the conformation around C2-C1 is gg and is more relaxed (distorted by 78) than in 1. For the comparison, in other known furanose structures of Amadori compounds, there is the tg arrangement in allyl 1-deoxy-1-[(1-methyl-2-benzoylvinyl)amino]-a-D-fructofuranoside, [38] gt (distorted by 218) in L-rhamnulosedibenzylamine, [35] and gg in 1-cyclohexylamino-1,6-dideoxy-a-D-tagatofuranose-6-C-sulfonic acid. [39] Torsion angles in the amino acid portions of 1 and 2 do not differ more than 258: the most significant conformational difference between the proline residues is observed around the N1-C7 bond ( Table 3).…”

“…Puckering parameters for the a-furanose ring in 2 are Q ¼ 0.3986 Å and w ¼ 148.458, and the pseudorotational parameters [34] are P ¼ 240.68, with t m ¼ 43.48 for the C3-C4 bond. In contrast, crystalline L-rhamnulose-dibenzylamine [35] was obtained from a diethyl ether/petroleum ether mixture as the b-anomer, with the fructofuranose ring in the 3 T 2 conformation. Both anomers equally populate the tautomeric equilibrium that establishes in the aqueous solution of L-rhamnulose-L-proline, according to the NMR measurements, [17] and both conformations fit well into the calculated energy minima for the respective furanose anomeric configurations.…”