A straightforward anionic coupling for the synthesis of ortho-bromobiaryls

Non-catalyzed anionic coupling of aryllithiums with 1,2-dibromobenzene gives straightforward access to valuable ortho-bromobiaryls.     

Exploring antibody polyspecificity using synthetic combinatorial libraries

Summary Extensive mapping studies for seven antigen-antibody interactions have been carried out using both individual analogs and peptide libraries. With competitive ELISA, these studies have revealed that monoclonal antibodies exhibit a broad range of specificities, from antibodies that recognize only conservative substitutions for 1–2 positions of the antigenic determinant, to antibodies that recognize sequences that are completely unrelated to the parent antigen with comparable affinities. Synthetic combinatorial libraries, containing millions of peptide sequences, permit a more systematic and rapid evaluation of the extent of multiple-binding specificities of monoclonal antibodies than individual analogs. The peptide libraries used here comprise mixtures of compounds having specifically defined positions and mixture positions. The same diversity of sequences in different formats, which differ by the numbers of positions singularly defined and different locations defined within the sequence, can be examined. Comparison of the screening results, selection criteria of the most active mixtures, and different approaches used for the deconvolution of active individual compounds are discussed. Synthetic combinatorial libraries greatly facilitate the understanding of antigen-antibody interactions at the amino acid level and will assist in the development of improved immunodiagnostics.     

Synthesis of Anti-Inflammatory α-Arylalkanoic Acids by 1,2-Aryl Shift. New Synthetic Methods (42)

α-Arylalkanoic acids have acquired importance as anti-inflammatory agents and are now in great demand on the pharmaceutical front. Hence, the need has arisen for new and improved, economical synthetic procedures suitable for their preparation and manufacture on an industrial scale. For many years the synthetic approach to this class of compounds was restricted to the Willgerodt and Darzen reactions. More recently, several methods have been developed which are based on the 1,2-aryl shift in acetals of α-functionalized alkyl aryl ketones. This new approach starts from the oxythallation of alkyl aryl ketones first described by Taylor and McKillop in 1971. Asymmetric syntheses of some important arylakanoic acids have also been developed on this basis. The highly toxic thallium salts may be replaced, inter alia, by catalytically effective metal salts.     

Asymmetric Diels-Alder and Ene Reactions in Organic Synthesis. New Synthetic Methods (48)

Rapidly accumulating evidence shows the value of asymmetric Diels-Alder and ene reactions for the syntheses of enantiomerically pure molecules. This article presents a systematic and critical treatment of various stereoface-differentiating principles, including very recent spectacular advances. The chiral information is mainly provided by covalently bound auxiliaries, some of which are crystalline, inexpensive, and readily available from naturally occurring monoterpenes, hydroxy acids, amino acids, steroids, and sugars. Non-destructive transfer of chirality leads to the efficient creation of up to four chiral centers with predictable relative and absolute configurations. Regenerative cleavage of the auxilary group from the diastereomerically pure adducts furnishes a range of polyfunctional, optically pure building blocks. Their synthetic potential is illustrated by strategic applications to the syntheses of physiologically interesting, chiral natural products such as prostaglandins, antibiotics, terpenoids, shikimic acid, alkaloids, and kainoids.     

New Methods of Preparative Organic Chemistry. Transfer of Diazo Groups

When an arenesulfonyl azide, particularly p-toluenesulfonyl azide, reacts, in the presence of a base, with a compound containing an active methylene group, the two hydrogen atoms of the active methylene group are replaced by a diazo group to form a diazo compound and an arenesulfonamide. The method may be used for the synthesis of the diazo derivatives of cyclopentadienes, cyclohexadienes, 1,3-dicarbonyl, 1,3-disulfonyl, and 1,3-ketosulfonyl compounds, ketones, carbonic acid esters, and β-iminoketones. Secondary reactions can lead to azo compounds and heterocycles such as 1,2,3-triazoles, 1,2,3-thiadiazoles, and pyrazolin-4-ones. Azidinium salts react in the same way, but in this case an acidic reaction medium is necessary, a fact that is sometimes advantageous.     

Directed Aldol Condensations

The present article describes the discovery of a new procedure for aldol condensations for the preparation of α,β-unsaturated carbonyl compounds

1 G. Wittig, H. Pommer, and W. Stilz, German Patent 1199252 (April 5, 1963), BASF; Chem. Abstr. 63, P 1739c (1965).

. The scope of this process is demonstrated by many examples, including some from the natural products sector; at the same time, however, these examples also mark its limitations. The metalated Schiff's bases may be classified as ambident anions; this also explains acylations on the nitrogen. A comparison of the new directed aldol condensation with the formation of unsaturated carbonyl compounds through olefination via phosphorylids shows that the latter method fails when a ketone is used as the substrate. This is where the described procedure using metalated Schiff's bases proves its value.     

药源性铅中毒浅谈

铅为有毒微量元素，广泛存在于空气，土壤，水源中，药物在种植，生产过程中有可能带入铅毒，加上病人用药不当，极易造成药源性铅污染。     

皮质激素侧链合成方法的新进展

综述了近五年来由１７－甾体酮基合成皮质激素侧链方法的进展。参考文献１４篇。     

应用模糊综合评判方法优选非均质油藏调剖井和层

通过注水保持油层压力的方法开发非均质油藏,不可避免会造成油井含水或部分油井水淹.注入水窜入油井时,不管低渗透层是否受到开发,大部分注入水进入到高渗透层,因而使低渗透层在开发过程中采油速度很慢,或是基本未投入生产.为了降低产水量,保持或提高采油量,必须对已开发的非均质油藏实施相应的堵水调剖措施,防止注入水沿高渗透带水锥突进到油井,影响水驱采收率.本文建立了应用模糊综合评判方法优选非均质油藏调剖井和层的数学模型,通过实例分析表明,运用综合评判方法优选调剖井和层是一种客观有效的方法,该评价方法计算方便,易于操作和推广.