Synthesis of polysaccharides. Communication 16. Synthesis of L-arabinopyranans

Summary The synthesis has been effected of 3-0-acetyl-4-0-trityl- and 4-0-acetyl-3-0-trityl-1,2-0-[(l-exo-cyano)ethylidene]-p-L-arabinopyranose by the polycondensation of which (1 4)-L-arabinopyranan and (1 3)-L-arabinopyranan were obtained containing 1,2-trans- and 1,2-cis-glycosidic bonds at a ratio 31.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 196–199, January, 1986.     

Synthesis of macrolide antibiotics. 20. Synthesis of erythronolide A

A complete, stereocontrolled synthesis for erythronolide A was carried out by fusion of the (C⁹-C¹³)+(C⁷-C⁸)+(C¹-C⁶) fragments from levoglucosan in 61 steps with 0.28% total yield.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 195–199, January, 1990.     

Enantioselective Synthesis of Pseudomonic Acids. I. Synthesis of Key Intermediates

An enantioselective synthesis of key intermediates for the synthesis of the anti-microbially active pseudomonic acids A ( 1 ), B ( 2 ) and C ( 3 ) is described. D -Ribose ( 4 ) was used as starting material.     

Synthesis of ent-alantrypinone.

This paper presents a synthesis of ent-alantrypinone (ent-6), the enantiomer of a natural product produced by the fungus Penicillium thymicola. The synthesis revolves around the Li[Me(3)AlSPh]-promoted isomerization of iminobenzoxazine 33 to quinazolinone 34, an N-acyliminium ion cyclization that converts enamide 9 to bridged indole 35, and rearrangement of 35 to oxindole ent-6. Ancillary chemistry that involves thermal fragmentation of an iminobenzoxazine to a nitrile ylide and Me(2)AlSPh-mediated cyclization of oxime ether-ester 22 to pyrrolidinone 23 is also described.     

Synthesis of Sugars From D-Ribonolactone. II. An Alternative Synthesis of D-Erythrose

D-Erythrose was synthesized in four steps from D-ribono-1,4-lactone via the 3,5-O-benzylidene derivative of the latter compound. Reduction of the benzylidene D-ribonolactone, and periodate cleavage of the resulting 3,5-O-benzylidene-D- ribitol were performed in a one-flask reaction. The ensuing 2,4-O-benzylidene-D-erythrose was hydrolyzed with 10% acetic acid to obtain syrupy D-erythrose.     

Synthesis of new fundamental heterocycles. Part VII. Synthesis of 2-azaxanthene

2-Azaxanthone ( 5 ) has been conveniently prepared by condensation of the morpholine enamine of 1-benzyl-4-piperidone witli salicylaldehyde followed by chromium trioxide oxidation and subsequent aromatization. Lithium aluminum hydride reduction of 5 afforded the new fundamental heterocycle 2-azaxanlhene.     

多官能团分枝状化合物的合成研究：Ⅴ.多烯烃体系的合成

以六溴甲基苯为核心,季戊四醇三烯丙基醚为支化单元,采用收敛法合成了六方向,具有１８个末端烯丙基的多烯烃体系。     

Synthesis of hydrothioxanthenes. I

It is shown that methylene dieyclohexanone reacts with phosphorus sulfides to give a mixture of tricyclic 6-membered ring sulfides: perhydrothioxanthene, 1, 2, 3, 4, 5, 6, 7, 8-octahydrothioxanthene, and thioxanthene. The behaviors of perhydroxanthene and sym-octahy-droxanthene toward oxidation, mercuric chloride, and dehydrogenation are investigated.