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Stereokontrolowana synteza tlenowych analogów penicylin i cefalosporyn

100%

Łysek R. , Furman B. , Borsuk K. , Chmielewski M.

Wiadomości Chemiczne

2003

tom [Z] 57, 5-6

391--433

Synthesis of oxacephalotin and oxacephamandol which are more active then natural, containing sulfur congeners, and isolation of clavulanic acid, a patent inhibitor of (3-lactamase enzymes, directed attention of academic and industrial laboratories to the synthesis of oxygen analogs of penicillins and cephalosporins. The present review directs attention to the stereocontrol of a desired configuration in the formation of the bridgehead carbon atom. Five possible methods leading to basic skeletons of the title compounds are discussed (Scheme 1). Three of them involve nucleophilic substitution at C-4 of the azetidin-2-ones performed as inter or intramolccular process, and two of them involve cycloaddition reactions between ketenes and iminoethers, or between vinyl ethers and isocyanates. Owing to the general application stereospecificity, and high asymmetric induction, the last method seems to be most advantageous. The weak point of the nucleophilic substitution methodology is that a nuclcophilc enters 3-substituted azetidin-2-one ring preferentially anti to the existing substituent or if there is no substitutent at C-3, stereoselectivity in generation of a new stereogcnic center at C-4 is low. All methods arc illustrated by examples taken from the literature.

Asymmetric Synthesis of Multi-substituted Indolizidines by Intramolecular Addition of Allylsilane to Chiral 2,3-Dihydro-4-pyridones

100%

Furman B. , Frelek J. , Dziedzic M. , Kamińska A.

2005

tom Vol. 79 / nr 12

1919-1928

A short and synthetically attractive asymmetric synthesis of substituted indolizidines is described. The discovered reaction sequence consists of the asymmetric aza-Diels-Alder reaction of aldimines with Danishefsky's diene and the intramolecular Hosomi-Sakurai allylation. The absolute configuration of cycloadducts was established by CD-spectroscopy

[2+2]Cycloaddition of Chlorosulfonyl Isocyanate to Chiral Vinyl Ethers

100%

Furman B. , Kałuża Z. , Łysek R. , Chmielewski M.

1999

tom vol. 73 nr 1

43-54

The asymmetric [2+2]cycloadditions of chlorosulfonyl isocyanate to vinyl ethers derived from sugars and hydroxy acids are presented. The account focuses on various aspects of the cycloaddition and on the transformations of the resulting [2+2]cycloadducts into clavams and 1-oxacephams. In order to rationalize the results of direction and magnitude of [2+2]cycloaddition, the stereochemical models of this reaction are discussed.

Synthesis of7-Substituted 5-Dethia-5-oxacephams via [2+2]Cycloaddition of Chlorosulfonyl Isocyanate to Sugar Vinyl Ethers

100%

Łysek R. , Furman B. , Kałuża Z. , Chmielewski M.

tom Vol. 74, nr 1

51-60

Subsequent transformations of adducts consisting in detritylation, tosylation of a terminal hydroxy group and intramolecular alkylation of the nitrogen atom give corresponding tetracyclic 5-oxacephams.

Rotifer communities in reservoirs created by sand extraction in the silesian upland

75%

Bielanska-Grajner I. , Gladysz A. , Furman B. , Gadomska A. , Kopaczynska-Nowacka K. , Zymelka I.

Teka Komisji Ochrony i Kształtowania Środowiska Przyrodniczego

2008

tom 05