The Crystal and Molecular Structure of Bicyclomycin, a New Antibiotic

Abstract

The molecular structure of a new antibiotic, Bicyclomycin (C12H18O7N2), has been elucidated by X-ray diffraction analysis. Bicyclomycin crystallizes from aqueous solution in two forms, an orthorhombic and a monoclinic systems. The crystal data for the former are a=11.72, b=12.72, c=8.80 Å and the space group P212121, while those for the latter are a=10.27, b=10.91, c=6.67 Å, β=101.4°, and the space group P21 The crystal structure of the former was solved by the direct method and refined by least-squares method to a final R factor of 0.07 for 1623 reflections. The established structure is (Remark: Graphics omitted.) The diketopiperazine ring is folded into a boat form. The conformations of the side chain are all gauche or nearly so. All the oxygen and nitrogen atoms participate in two intramolecular and four intermolecular hydrogen bonds.

Bicyclomycin: synthetic, mechanistic, and biological studies

“…All other entries in the table were done with HMPA. 6 Reaction time refers to the time the anion was stirred at -78 "C before addition of the electrophile. ' Yield is based on recovered starting material.…”

“…The alternative regioisomers 199 can be accessed via a fivestep one-pot protocol involving in situ generation of the trimethylsilyl species (at Ha) followed by carbanion " Yield is based on recovered starting material. 6 The product 13 was directly obtained form 2 by a three-step, one-pot procedure. formation at Hb, electrophilic quench (to 205), and fluoride removal of the C-trimethylsilyl protection.…”

Syntheses and NMR behavior of calix[4]quinone and calix[4]hydroquinone

“…Acetylation of 6a (25 mg, 0.047 mmol) with Ac20/pyridine (2:1, 15 mL) gave the undeca-O-acetate of validamycin G (6c, 20 mg, 54.5%): NMR (CDClg, 400 MHz) 1.49 (1 H, dd, J 2.7,15.3 Hz, 6-Hax), 1.90 (1 H, dd, J 3. 1,15.3 Hz,; 1.99, 2.00, 2.03, 2.04, 2.05, 2.06, 2.06, 2.07, 2.08, 2.10, and 2.14 (each 3 H, s, acetyl X 11); 3.43 ( 1H, dt*,«/2.7,3.1,4.4 Hz, 1-H), 3.60 (1 H, m, l'-H), 3.63 (1 H, ddd, J 2.3, 4.1, 9.1 Hz, 5"-H), 3.66 (1 H, d, J 9.9 Hz, 4-H), 3.92 and 4.13 (each 1 H, ABq, J 11.1 Hz, 7-H), 4.04 (1 H, dd, J 2.3,12.5 Hz) and 4.40 (1 H, dd, J 4.1,12.5 Hz) (6"-H), 4.37 and 4.60 (each 1 H, hr ABq, J 13.3 Hz, 7-H), 4.50 (1 H, d, J 9.1 Hz, 1"-H), 4.93 (1 H, dd, J 4.4, 9.9 Hz, 2-H), 4.97 (1 H, t, J 9.1 Hz, 2"-H), 4.99 (1 H, dd, J 5.1,10.2 Hz, 2'-H), 5.09 (1 H, t, J 9.1 Hz, 4"-H), 5.16 (1 H, t, J 9.1 Hz, 3"-H), 5.38 (1 H, br d, J 6.6 Hz, 4'-H), 5.42 (1 H, dd, J 6.6,10.2 Hz, 3'-H), 5.52 (1 H, t, J 9.9 Hz, 3-H), 5.97 (1 H, br d, J 5.1 Hz, 6'-H), 5.87 (1 H, br s, -NH-) (*apparent splitting pattern).…”

“…Since the first paper of Gutsche on calixarenes3 was issued, we have been studying the syntheses of various calixarenes and their characteristics.4 On the other hand, we have been searching for a new redox system. If calix- [4]hydroquinone (6) and calix [4]quinone (7), which are calixarene-type compounds comprised of cyclic arrays of p-hydroquinone residues and p-quinone residues attached by methylene groups, respectively, are synthesized from readily available p-tert-butylcalix [4] arene, they not only form new redox systems but also become new compounds which are able to form charge-transfer complexes.5 Thus, we finally found a convenient synthesis of 6 and 7. In this paper we report their synthetic methods using three different pathways and their NMR behavior.…”

“…In chlorobenzene the Fries rearrangement of 37,38,39,40,41,42-hexaacetoxycalix[6]arene has been reported not to take place.8 However, we used nitrobenzene as a solvent for the rearrangement of 2 to 3. The calixarene 3 was allowed to react with acetic anhydride in the presence of sodium acetate to give 5,11,17,23-tetraacetyl-25.26.27.28-tetraacetoxycalix[4]arene (4) in 76% yield. The Baeyer-Villiger oxidation of 4 to 5,11,17,23,25,26,27,28octaacetoxycalix[4]arene (5) using perbenzoic acid required prolonged times in the dark, with occasional shaking at room temperature for completion.…”