改进的1,3-缩水-2,4-二-氧-苄基-β-L-鼠李糖及1,3——缩水-2,4,6-三-氧-苄基-β-D-甘露糖的合成

用相应二丁基锡络合物对α-L-鼠李糖烯丙基苷及α-D-甘露糖烯丙基苷进行选择性3-氧-烯丙基化. 用(Ph~3P)~3RhCl催化脱烯丙基并苄基化得到相应的苄基化1,3-二醇. 再进行乙酰化,氯化,接着进行关环反应,得到1,3-缩水苄基内醚糖.     

1,3,4,6-tetracarbonyl compounds. 3. synthesis, structural features, and antimicrobial activity of 1,6-diaryl-3,4-dihydroxy-2,4-hexadiene-1,6-diones

The Wittig reaction of 5-aryl-2,3-dihydro-2,3-furandiones with aroylmethylenetriphenylphosphoranes is regioselective and leads to the formation of 5-aryl-2-aroylmethylene-2,3-dihydro-3-furanones. In the presence of acid the products react with water, giving satisfactory yeilds of 1,6-diaryl-3,4-dihydroxy-2,4-hexadiene-1,6-diones. The latter were also obtained by the reaction of 2,3-furandiones with alkylnitroamines. The base-catalyzed condensation of 2,3-furandiones with acetophenones led to 1,6-diaryl-3,4-dihydroxy-2,4-hexadiene-1,6-diones, which exist in DMSO solution in equilibrium with the cyclic oxo tautomers —substituted 2-hydroxy-2,3-dihydro-3-furanones. Some of the synthesized compounds exhibit antimicrobial activity toward standard strains ofStaphylococcus aureus andEscherichia coli.For Communication 2, see [1].Perm Pharmaceutical Academy, Perm, Russia; e-mail: kvo@pi.ccl.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1466–1475, November, 1999.     

Reactions of 1,6-anhydro-3,4-dideoxy-2-O-methyl-β-d-threo-hex-3-enopyranose with thiols and methanol

Thiolysis and methanolysis of 1,6-anhydro-3,4-dideoxy-2-O-methyl-β-d-threo-hex-3-enopyranose yield anomeric thio- and methyl glycosides, respectively, and an acyclic product (in the reaction with EtSH). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 549–552, March, 1997.     

Selective synthesis and ester cleavage property of 3,2-anhydro-3-deoxy-3-thio-β-cyclodextrin

The title compound was synthesized by the conversion of 2^A,3^A-alloepoxy-β-cyclodextrin to the 2^A,3^A-mannoepithio derivative with thiourea and subsequent ring-opening by intramolecular nucleophilic substitution. Its thiol group and the distorted cavity demonstrated good synergetic effect in promoting the cleavage of m-nitrophenyl acetate but did not cooperate with each other toward the p-isomer.     

Stereoselective synthesis of 2,2-bis(C-branched-chain) glucopyranosid-3-ulose via autoxidation reaction

Many different approaches for synthesis of branched chain sugars have beenestablished,1 because they are very useful intermediates for synthesis of other non-sugar chiralmolecules, and usually occur in nature. Branched chain glycosidulose can be used for construction offive- and six-membered carbocyclic rings to which two chiral carbons of sugar are incorporated byintramolecular aldol condensation and Robinson annulation,2 Therefore they are useful in thesynthesis of natural products which consist of annulated carbohydrates or where a highlyfunctionalised enantiomerically pure cyclopentane or cyclohexane is required. Also, this type ofbranched chain sugar can be considered as the synthons of monoterpenoid natural products of theiridoid class which have the cyclopentan-(c)-pyran structure. In view of the importance of branchedchain glycosiduloses, it is desirable to have a general, convenient methodology to their synthesis.However, none of the literature methods was reported on their synthesis by a nuclephilic addition toa partially protected glycosidulose, due to the fact that these glycosiduloses are very difficult tosynthesize selectively and unstable;3 and what is more, one-step synthesis branched chainglycosidulose using this method is almost impossible.In this paper, we report on a general, convenient method for stereoselective syntheses of2,2-bis(C-branched-chain)glucopyranosid-3-uloses by the new reaction of 1 with various activemethylene compounds. The generality of this method was examined in detail. The optimumtemperature was 18-25℃. The solvent DMF was better than the others. In all cases he yields werehigher than 60%.All the 2,2-bis(C-branched-chain)glucopyranosid-3-uloses were characterized by X-raycrystallographic analyses. In addition, the important iintermediate in this reaction was isolated,which is the product of autoxidation of 1 at C-3 position. Thus the reaction mechanism for thesynthesis of 2,2-bis(C-branched-chain) glucopyranosid-3-uloses can be rationalized by autoxidationof 1 followed by 1,4-Michael addition of various carbanions as the main steps.     

Stereospecific synthesis of aryltetraline lignan analogues using 1,6-bis(dipropylboryl)hexa-2,4-diene

A novel convenient two-stage synthesis of aryltetraline lignin analogues from aromatic aldehydes and diallyl diboron derivatives on the basis of intramolecular Friedel–Crafts reaction has been developed.     

A Practical Synthesis of 2,4-Dichloro-3-methyl-6-nitrophenol

2,4-Dichloro-3-methyl-6-nitrophenol 2 was prepared by KOH/H₂O hydrolysis of a product mixture obtained from chlorination of p-nitrotoluene in the presence of a phase transfer catalyst. A 95–99% yield of 2 based on 2,3,6-trichloro-4-nitrotoluene, 4 (major chlorination product) was achieved in >95% purity.     

Stereoselective synthesis of 2,2-bis(C-branched-chain)glucopyranosid-3-ulose via an autoxidation-Michael addition reaction

2,2-Bis(C-branched-chain)glucopyranosid-3-uloses, designed for the preparation of biologically active natural product iridoid derivatives, are synthesized selectively by the new reaction of butenolide-containing sugar with active methylene compounds, and the new reaction is clarified as autoxidation followed by Michael addition of carbanion.     

A highly conductive and crystalline graphite-like polymer from 2,4-hexadiyn-1,6-diol

Poly-(2,4-hexadiyn-1,6-diol) (PHDO), prepared by NbCl₅/(n-Bu)₄Sn catalyzed metathesis of HDO, was pyrolyzed at various temperatures and electrical and structural properties of resulting polymers were investigated by FT-IR, Laser Raman, CP/MAS ¹³C-NMR and X-ray diffraction methods. The polymer obtained by pyrolysis of PHDO at 800°C showed a conductivity of about 10 S/cm at room temperature. The structure of the polymer seems to be a graphite-like crystal consisting of condensed aromatic layers. © 1994 John Wiley & Sons, Inc.     

Solid-state thermal polymerization of 2,4-hexadiyne-1,6-diol

The solid-state thermal polymerization of 2,4-hexadiyne-1, 6-diol has been studied by a variety of methods. Pure monomer heated under vacuum or in an inert gas atmosphere is found to polymerize readily, unlike material heated in air. X-ray diffraction reveals that samples anneal during polymerization. Initially, a long chain polymer is formed, but above 20% conversion a less perfect product is obtained. Measurements suggest a complex molecular rearrangement during the nonideal phase of polymerization. Possible models for this process are discussed.     

Asymmetric synthesis of cis-2,4-disubstituted azetidin-3-ones from metal carbene chemistry

Several chiral cis-2,4-disubstituted azetidin-3-ones were prepared as single diastereoisomers from N-protected amino acids, employing a highly stereoselective copper carbenoid N–H insertion reaction of diazoketones. These azetidin-3-ones were then converted into fully substituted azetidines in a few steps in good to high yields.