Hypoglycemic 5-furyl and 5-thienyl derivatives of oxazolidine-2,4-dione and the pharmaceutically-acceptable salts thereof; certain 3-acylated derivatives thereof; and intermediates useful in the preparation of said compounds.
Cycloadditions of 3-methoxyfuran (1) with several mono-activateddienophiles gave the endo adducts stereoselectively under the usual conditions in satisfactory yields; two of the adducts were transformed into potential intermediates (7a) and (7b) for the synthesis of (±)-avenaciolide and (±)-isoavenaciolide, respectively.
Reversible carbon protonation in the hydrolysis of heterocyclic enol methyl ethers
作者:Brian Capon、Fu-Chiu Kwok
DOI:10.1016/s0040-4020(01)89931-2
日期:1987.1
The kinetics of the hydronium-ion catalysed hydrolysis of the following heterocyclic methylenolethers have been measured: 3-methoxybenzofuran, 3-methoxybenzothiophene, 3-methoxy-indole, 3-methoxy-1-methylindole, 3-methoxyfuran, 3-methoxythio-phene, and 2-methoxythiophene. On the basis of the solvent isotope effect = 3.08 and the failure to detect deuterium exchange when the solvent was CD3CD:D2O(9:1
已经测量了以下杂环甲基烯醇醚的水合氢离子催化的水解动力学:3-甲氧基苯并呋喃,3-甲氧基苯并噻吩,3-甲氧基-吲哚,3-甲氧基-1-甲基吲哚,3-甲氧基呋喃,3-甲氧基硫代-酚和2-甲氧基噻吩。根据溶剂同位素效应= 3.08以及当溶剂为CD 3 CD:D 2 O(9:1 v / v)时检测不到氘交换的结论,得出结论,3-水解中的限速步骤甲氧基苯并呋喃是C-质子化。通过比较3-甲氧基-苯并呋喃的水解速率和3-甲氧基茚的水解速率(快2100倍)来测量环氧原子的作用。
A Practical, Enantioselective Synthetic Route to a Key Precursor to the Tetracycline Antibiotics
作者:Jason D. Brubaker、Andrew G. Myers
DOI:10.1021/ol071377d
日期:2007.8.1
synthetic route to a key precursor to the tetracycline antibiotics is reported. The route proceeds in nine steps (21% yield) from the commercial substance methyl 3-hydroxy-5-isoxazolecarboxylate. Key steps in the route involve enantioselective addition of divinylzinc to 3-benzyloxy-5-isoxazolecarboxaldehyde and an endo-selective intramolecular furan Diels-Alder cycloaddition reaction. The route described