New Synthetic Route to Pummerer's Ketone

Pummerer's ketone 1 is obtained with an overall yield of 55 % by the following sequence: Claisen rearrangement of an arylcyclohexylether 3; allylic oxidation of the methylcycloalkylphenolic derivative 4b, then spontaneous cyclisation during demethylation to give 2. 1 is obtained by dehydrogenation of 2. NMR data agree with a cis stereochemistry at C_4a and C _9b.     

A New Synthetic Route to 5-Isoxazolamines

5-Isoxaz0lamineshavebeenusedasintermediatesforthesynthesis0fderivatives0fantihistaminic,analgetic,antibacterial,insecticidal,herbicidalandfungicidalactivity'.Usuallytheyaresynthesizedbytheintramolecularcondensation0fhydr0xylamineand0-nitrilegr0up'.Otherapproaches,suchasreductivecyclizati0nofZ-a-cyano-6-nitroethylenesandIithiumaIuminumhydridereduction0f3-cyanooxazoleshaveals0beenrepoFted'-'.HerewerepoFtanewsyntheticrouteofthesecompounds.Ohn0andNaruse7havereportedthatthereactionof2-chlorocycl…     

A New Synthetic Route to Selected Indenones

Indenones are useful intermediates in the synthesis of several natural products, e.g. gibberellins (1) and steroid hormones with a C-nor-D-home system (2). Despite the nernerous methods for indenone synthesized, or the yields was much lower as mentioned in earlier reports (1)(4). One of the difficulties of the usual methods is the required electrophilic cyclization meta to a methoxyl substiruent. House (5) deals with these difficulties in more detail. In our method the synthesis of 6-methoxyinde-nones is effected by substitution dara to methoxyl function.     

4-溴代苯酐的合成新方法

将4-硝基邻苯二甲酰亚甲胺（4-NPI）用铁粉还原为4-氨基邻苯二甲酰亚甲胺 ，再在氢氧化钠水溶液中水解成4-氨基邻苯二甲酸钠。4-氨基邻苯二甲酸钠在氢溴 酸中经Sandmeyer反应合成4-溴代苯酐。产品纯度高，是合成4-溴代苯酐的一个比较 理想的方法。     

邻氯苯甲腈的新合成法

以邻氯溴苯为起始原料,选用K4[Fe(CN)6]为氰基化试剂,Pd/C催化反应制得邻氯苯甲腈。 考察了温度、碱、催化剂的用量和原料比等对反应的影响,确定了较佳反应条件。 邻氯溴苯转化率达98.5%,产物邻氯苯甲腈得率95.1%。     

一种合成3,5-二氨基吡啶及3,5-二甲氧羰基氨基吡啶的新路线

以3,5-二甲基吡啶为起始原料,经氧化、酰胺化,酰胺在不同的霍夫曼降解条件下合成3,5-二氨基吡啶及3,5-二甲氧羰基氨基吡啶,总收率分别为64%和68%。利用1H NMR、MS/MS、IR等方法对各化合物的结构进行了表征。讨论了氧化反应及霍夫曼降解反应的主要影响因素。反应均在常压下进行,反应条件温和,后处理简单,效率高。     

3-丙烯酰基-1,3-噁唑烷-2-酮的合成

3-α,β-不饱和酰基-1,3-噁唑烷-2-酮在烷基化及Diels-Alder等反应中在手性催化剂的存在下,产物都有较高的对映选择性。但3-丙烯酰基-3,3-噁唑烷-2-酮极易聚合,现有制备方法结果均不理想。本文将丙烯酸与丙烯酰氯在三乙胺的存在下生成酸酐,再在无水氯化锂的作用下与1,3-噁唑烷-2-酮在室温反应,反应结束后直接将反应混合物通过硅胶柱色谱进行层析分离得到3-丙烯酰基-1,3-噁唑烷-2-酮,产率达83％。合成路线如下：     

New Synthetic Route to Cinnoline Derivatives and Their Microbiological Activity

Russian Journal of Organic Chemistry - New cinnoline derivatives have been synthesized by reductive cyclization of hydrazones obtained by condensation of various 2-nitrophenylhydrazine derivatives...     

磷酸特地唑胺的合成新方法

以(5R)-3-(4-溴-3-氟苯基)-5-羟甲基噁唑烷-2-酮为起始原料,在[PdCl₂(dppf)]·CH₂Cl₂催化下与联硼酸频那醇酯反应得到硼化物,继而与5-溴-2-(2-甲基-2H-四唑-5-基)吡啶进行Suzuki反应得到特地唑胺,收率82.9%。 分别考察了催化体系对硼化反应和Suzuki反应的影响,确定了较佳的反应条件。 特地唑胺与二苄基N,N-二异丙基亚磷酰胺反应得到二苄基保护的磷酸特地唑胺,随后经Pd/C脱苄得到磷酸特地唑胺,总收率66.2%。     

Novel Synthetic Route to Fluoxetine

Racemic fluoxetine was synthesized from 3-benzoylpropionic acid in five steps in 54% overall yield.     

Synthetic Route to Ergot Alkaloids

Rye is sometimes infected by a fungus called Claviceps purpurea. The term ergot designates the dark, brown, tuberous bodies which can be collected before or during harvesting and represent one of the most remarkable drugs of our therapeutic arsenal. Actually, the most significant alkaloids are metabolic products of these fungi. We elaborated three alternative total synthetic pathways to construct the ergoline skeleton, one of which – suitable for scaling up – finally resulted in (+)‐lysergic acid ( 32a ) and α‐ergocryptine ( 1 ) (Schemes 5 and 6).     

New Efficient and Flexible Synthetic Route to Emivirine and Its Analogs

A revised synthetic route to Emivirine (MKC‐442) via properly substituted β‐keto ester converted from Meldrum's Acid was developed. This method could be applied to the synthesis of a variety of MKC‐442 analogues and open the way for their systematic biological evaluation.     

A New Synthetic Route to 12-Oxo-1, 15-pentadecanlactam

12-Oxo-1,15-pentadecanlactam 7 was synthesized from cyclododecanone with a totalyield of 36% in a seven-step reaction. The azide 5 to 12-nitro-1,15-pentadecanlactam 6 is the key step featured by direct ring expansion.     

A New Synthetic Route to (±)-Perhydrohistrionicotoxin

Starting from ethyl 2-cyclohexen-1-carboxylate ( 3 ) the total synthesis of the perhydrohistrionicotoxin intermediate 23 was achieved in 25% overall-yield. The two key steps involve a positionally specific addition of HOBr to the oxime-olefin 7 and the alkylation of bromooxime 17 with 1-lithio-1-butyne. The latter represents a novel method for stereospecific and position-specific introduction of a nucleophilic butyl equivalent in α-position to a ketonic carbonyl group.     

A Facile Synthetic Route to L-Phosphinothricin

Phosphinothricin, the active ingredient of the well known broad-spectrum herbicideglufosinate-ammonium, is a naturally occurring amino acid possessing the uniquemethylphosphinate moiety, and its strong herbicidal activity has been attributed to anability to inhibit glutamine synthetase in plants and bacteria1. Further research showedthat L-enantiomer of phosphinothricin was the carrier of the activity, whereas the D formonly had a small action2, therefore the stereoselective synthesis of L-pho…