It has been found that a change in the protective group affects the solid structure of septanoins. Thus, the structure of methyl-2,3,4,5-tetra-o-acetyl-α-d-glucoseptanoside 5 adopted a twist-chair conformation compared to other glucose panosides α-d previously mentioned…
It has been found that a change in the protective group affects the solid structure of septanoins. Thus, the structure of methyl-2,3,4,5-tetra-o-acetyl-α-d-glucoseptanoside 5 adopted a twist-chair conformation compared to other glucose panosides α-d previously mentioned . The C1-O1 fixation length of 1.388 Å in 5 was shorter than C1-O6 (1.415 Å) and C6-O6 (1.411 Å) due to the anomer effect. The fixing angles inside the ring of seven glosses were greater than the ideal tetrahedral value often seen in septanoside structures. In addition, the average fixation angles of odd numbered carbons (113.7 °) were lower than those of even carbon atoms (114.3 °). An analysis of the torsional angles inside the seven-memory ring revealed a twist-chair deformation (Table 6), in particular a 4.5TC6.0 deformation in which the axis of symmetry passed through C2. The torsional angles observed with the septanosidic ring corresponded to the calculated torsional angles of the cycloheptan-twist-chair deformation. The ORTEP diagram and the torsional angles of the seven-member ring are shown in Table 6. Recently, analysis of the preparation structure and solid structure β-d-glucoseptanose-pentaacetate 10 has been reported . Analysis of the torsional angle of 10 showed that it corresponded to Oxepan`s torsional angles (Table 11). The crystal structure of 10 was determined and the conformation of the ring was found as Twist-Chair, 5.6TC3.4 in which the axis of symmetry passed through C1.
The ORTEP diagram (40% probability) and the torsional angles of the septanossidic ring are shown in Table 11. The solid structure of methyl-5-O-acetyl-2-O-benzo-3,4-O-isopropylidene-β-l-idoseptanoside 11 has been reported (Table 12) . The needle crystal belonged to the orthorhombic group P21 21 21 with four molecules in the single cell. The presence of an anomer effect led to the fixing lengths C1-O1 of 1.361 Å and O6-C1 of 1.42 Å. The continuous positive and negative signs of the torsional angles corresponded to the calculated Oxepan values (Table 12), which indicated a Twist-Chair deformation. The values of the torsional angles C3-C4-C5-C6 of -49° and C4-C5-C6-O6 of -32° defined the average square plane composed of atoms C4, C5 and C6. The conformation was therefore assigned to 0.1TC2.3. Stevens and his employees also reported on the crystal structure of methyl-β-d-gluptanozide 8 . The colorless crystals of 8 belonged to the monoclinic system with a P21 chamber group. The C1-O1 fixation length of 1.389 Å was shorter than C1-O6 (1.409 Å) and C6-O6 (1.425 Å), which corresponded to theoretical predictions of an annumerous pyranosiden β. The torsional angles inside the septanosidic ring indicate that a stool conformity was assumed to be 2C5.6 (Table 9).
Crystal structures of septanoses and septanosides showed that the ring in most cases took on a Twist-Chair conformation. Septanoses α and β-d/l accept conformations of chairs and swivel chairs. The variation in deformation was generally attributed to the action of the protection groups and the flexibility of the ring. One of the first crystal structures of septanoside was the ratio of Sundaralingam and employees to 1,2:3,4-di-O-isopropylide-5-O-chlor-acetyl-α-d-glucoseptanoside 2 . . . .