Dehydrogenative N‐Incorporation: A Direct Approach to Quinoxaline N‐Oxides under Mild Conditions

An efficient method for the synthesis of quinoxaline N‐oxides proceeds by the dehydrogenative N‐incorporation of simple imines by C(sp²)? H and C(sp³)? H bond functionalization. The overall transformation involves the cleavage of three C? H bonds. The reaction is easily handled and proceeds under mild conditions. Simple and readily available tert‐butyl nitrite (TBN) was employed as the NO source.     

Alcohol‐Selective Oxidation in Water under Mild Conditions via a Novel Approach to Hybrid Composite Photocatalysts

The oxidation of alcohols to carbonyl compounds in a clean fashion (i.e., with water as a solvent or under solvent‐free conditions, and using O₂ or H₂O₂ as the primary oxidant) is the subject of considerable research efforts. A new approach for the selective oxidation of soluble aromatic alcohols in water under mild conditions via a novel composite photocatalyst has been developed. The catalyst is synthesized by grafting 4‐(4‐(4‐hydroxyphenylimino)cyclohexa‐2,5dienylideneamino)phenol and silver nanoparticles onto the surface of moderately crystalline titanium dioxide. The titanium dioxide‐based composite was first extensively characterized and then employed in the catalytic oxidation of 4‐methoxybenzyl alcohol to 4‐methoxybenzaldehyde under UV irradiation in water at room temperature. The corresponding aldehyde was obtained with unprecedented high selectivity (up to 86 %). The method is general and opens the route to fabrication of photocatalytic composites based on titanium dioxide functionalized with shuttle organic molecules and metal nanoparticles for a variety of oxidative conversions.     

A New Approach to a-Bromochalcones

a-Bromo benzoylmethylene triphenylphosphorane 3 has been synthesized by the reaction of benzoylmethylene triphenylphosphorane 1 with N-bromosuccinimide in the yield of 87% and can react with aromatic aldehydes 4 to giveα-bromochalcones 5 in good yields.     

A New Approach to Glycopeptides

In only three or four steps glycosylated dipeptide and tripeptide fragments, respectively (see scheme), can be obtained from hydroxy amino acids by using a novel protecting group/activation concept. The method presented is even superior to the pentafluorophenyl ester method.     

A New Mild Reducing Agents of Nitroxide to Hydroxylamine

This work reports a new mild reducing agents of 2,2,6,6-tetramethylpiperidine-1-oxyl (1) to hydroxylamine with a good yield. These compounds are: tetrahydroxy-1, 4-quinone (3), 2,5-dihydroxy- 4-benzoquinone (4) and rhodizonic acid (5).     

A Study of the Thorpe-Ziegler Reaction in Very Mild Conditions

The Thorpe-Ziegler reaction has been used in the preparation of enaminonitriles and cyclic ketones for many years. A wide variety of bases¹ have been employed to acomplish this reaction, the most effective being the alkali metal salts of aralkyl amines. The reaction conditions vary from room temperature to toluene reflux temperature for long periods of time¹.     

A New Synthetic Approach to Elvucitabine

A new synthetic approach to elvucitabine started from L-xylose via the reactions of 10 steps in an overall yield of 20% was developed. The key steps included trimethylsilyl trifluoromethanesulfonate(TMSOTf)-mediated stereocontrolled β-glycosidation and exquisite choice of chloroacetyl group for the protection of hydroxyl groups as well as the corresponding deprotection under notably mild conditions. The structure of elvucitabine, in particular, the stereochemistry thereof, was unambiguously determined by comparison of the physical properties, such as ¹H NMR data and the specific rotation, of the synthesized sample with those reported.     

茶螺烷酮合成的新工艺

以α-紫罗兰酮为原料,经间氯过氧苯甲酸环氧化、甲醇钠开环、超声波辐射Pd/C催化甲酸铵选择性碳碳双键加H、硼氢化钠还原、脱水环化及乙酰丙酮亚钴催化烯丙位氧气氧化等6步反应,以总收率52.6％合成了食用香料2,6,10,10-四甲基-1-氧杂-螺[4.5]-6-癸烯-8-酮(茶螺烷酮)。 用IR、1H NMR、MS谱及元素分析等测试技术表征了产物的结构和组成。     

异黄酮类化合物的合成新方法

提出了一种新颖的合成异黄酮类化合物1, 2和3的方法. 以1,3-二甲氧基苯或1,3,5-三甲氧基苯为原料, 经Hoesch反应或Friedel-Crafts酰化反应、脱甲基反应、增碳关环一系列反应得到关键的甲氧基异黄酮化合物, 然后甲氧基异黄酮经过不同浓度氢溴酸的选择性水解反应制得含一个或多个羟基的异黄酮类化合物.     

A New Synthetic Approach to Salmeterol

In the present work a short and convenient route for the synthesis of salmeterol from salicylaldehyde has been developed.     

清洁工艺生产铅

一种新的湿法炼铅方法——碳酸化转化法，铅转化率达９０％以上，元素硫生成率为８０％以上。ＰｂＣＯ３可电解成金属铅或制成１０种铅化工产品。元素硫便于储存和运输。矿石中的ＦｅｘＳｙ对转化有催化作用。该方法彻底消除了火法炼铅过程中铅蒸气和二氧化硫对环境的污染，实现了清洁生产。     

A New Approach to Pyrrolidine and Piperidine Alkaloids

An uhexpected success involving the rearrangement of N-benzoyl2-pyrrolidone(1)to 2-phenylpyrroline (2)¹ provided us with an imaginative heuristic upon which some novel entries into the pyrrolidine and piperdine alkaloids was based.     

Partial Oxidation of Alcohols to Aldehydes and Ketones Under Mild Conditions

Abstract

A number of aldehydes and ketones were prepared by partial oxidation of alcohols in air catalyzed by RuO₂/ZSM‐5 which can be easily prepared with the industrial grade ZSM‐5 and RuCl₃ · xH₂O.     

Development of a Mild and Versatile Directed Cycloaddition Approach to Pyridines

The aza‐Diels–Alder cycloaddition of 1,2,4‐triazines with alkynes offers a rapid and convenient method for the synthesis of highly substituted pyridines, but often requires harsh conditions and long reaction times. The present study offers a solution to these limitations by use of a temporary tether established by a Lewis acid–base complexation of in situ generated alkynylboranes and triazines bearing a Lewis basic donor. The cycloaddition reactions take place within 20 min at 40 °C and provide direct access to a broad range of pyridines with complete and predictable regiocontrol. The carbon?boron bond can be further functionalised by cross‐coupling allowing further functionality to be introduced after cycloaddition.