3-O-Benzoyl-1,2-O-isopropylidene-β-D-fructopyranose

Abstract

In the structure of the title compound, C16H20O7, the five‐membered 1,3‐dioxolane ring is disordered with two different positions, A and B (1/1); it adopts the OT4 conformation slightly distorted towards E4 for mol­ecule A, and the 1E conformation distorted towards 1TO for mol­ecule B. The pyran­ose ring adopts an almost ideal 1C4 conformation. The three‐dimensional packing is stabilized by strong inter­molecular O—H⋯O inter­actions and weak C—H⋯O hydrogen bonds.

Total Synthesis of Two Pyrrole Spiroketal Alkaloids: Pollenopyrroside A and Capparisine B

“…13 C NMR data of synthetic 2 were in full agreement with those of the natural product capparisine B, 1b including the shifts of C-3 and C-6 (35.8 and 64.5 ppm) in the same deuterated solvent. Similarly, 13 C NMR data of synthetic 1 was also consistent with …”

“…In the S-diastereoisomer at C-2, the α-pyranose ring adopts 2 C 5 chair conformation to fulfill the anomeric effect, and the coupling constants (J 3,4 = 7.8 Hz and J 4,5 = 3.1 Hz) are consistent with Langer's study (J 3,4 = 10.1 Hz and J 4,5 = 3.4 Hz). 13 The difference between coupling constants may be caused by a slight distortion of fructopyranose ring. The distance between H-1 and H-4 was 2.381 Å, whereas the distance between H-1 and H-3 was 3.905 Å (Figure 2, a).…”

“…By comparing the NMR spectra, optical rotation, and melting points with reported values, the synthetic compounds 1 and 2 were identified as pollenopyrroside A and capparisine B, respectively. The chemical shifts of 13 C NMR signals are summarized in Table 2. The main differences in the 13 C NMR spectrum between isomers 1 and 2 were chemical shifts of C-3 and C-6 owing to the influence of adjacent C-2, whereas the chemical shift differences for the other carbon atoms were all within 1 ppm.…”

“…The chemical shifts of 13 C NMR signals are summarized in Table 2. The main differences in the 13 C NMR spectrum between isomers 1 and 2 were chemical shifts of C-3 and C-6 owing to the influence of adjacent C-2, whereas the chemical shift differences for the other carbon atoms were all within 1 ppm. 13 C NMR data of synthetic 2 were in full agreement with those of the natural product capparisine B, 1b including the shifts of C-3 and C-6 (35.8 and 64.5 ppm) in the same deuterated solvent.…”