Diazabicycloalkanes with nitrogen atoms in the nodal positions. 3. The benzo[b]-1,4-diazabicyclo [2.2.2]-octene system

Benzo[b]-1,4-diazabicyclo[2.2.2]octene and 4′-methylbenzo[1′,2′-b]-1,4-diazabicyclo[2.2.2]octene were synthesized by the reaction of N-acetyl-6-H- and 6-methyl-1,2,3,4-tetrahydroquinoxalines with ethylene oxide and subsequent cyclization of the N-(β-hydroxyethyl)-N'-acetyl derivatives in refluxing HBr. The errors of the published data on the benzo[b]-1,4-diazabicyclo[2.2.2]octene system are demonstrated. See [1] for communication 2. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 827–830.     

Determination de la configuration absolue de quelques derives du bicyclo[2.2.2]octane: Utilisation comparee de la regle des octants et de la methode d'horeau

A series of bicyclo[2.2.2]octane derivatives whose absolute configurations are known through chemical correlations with confirmed reference products (bicyclo[2.2.2]octanol, bicyclo[2.2.2]octene carboxylic acid) have been prepared.     

Trimethylsilyl group directed wagner-meerwein rearrangement of bicyclo[2.2.2]octan-2-ol derivatives

Trimethylsilyl group substituted bicyclo[2.2.2]octane derivatives were synthesized and subjected to TMS group directed Wagner-Meerwein rearrangement to give bicyclo[3.2.1]octene derivatives in high yields.     

An Unexpected Double Diels–Alder Reaction of (E)‐2‐Bromo‐4‐aryl‐1,3‐pentadiene Involving [1,5]‐Hydrogen Migration and HBr Elimination: Synthesis of Bicyclo[2.2.2]octene Derivatives

An unexpected double Diels–Alder (DDA) reaction of (E)‐2‐bromo‐4‐aryl‐1,3‐pentadiene was developed and resulted in a series of “butterfly‐like” bicyclo[2.2.2]octene derivatives in moderate to good yields without the need for a metal catalyst. The proposed mechanism involves a [1,5]‐sigmatropic hydrogen migration and HBr elimination. Through this decisive [1,5]‐hydrogen shift step, the electronic properties and steric hindrance of the conjugated diene substrate are completely altered and the DDA reaction of this potential diene synthon is successfully achieved.     

One and two hydrogen atom migrations in the retro-diels-alder fragmentation of norbornene and bicyclo [2.2.2] octene derivatives under electron impact

Norbornene derivatives with one or two carbonyl-containing substituents at positions 5 and 6 (anhydrides, esters, amides, cyclic ketones) undergo an electron impact induced rerro-Diels-Alder fragmentation accompanied by the migration of one hydrogen atom (RDA + H) giving rise to the [dienophile + H]⁺ ions. Bicyclo[2.2.2]octene derivatives substituted at C(5) and C(6) by a ring with two carbonyl groups (anhydrides, imides, diketones) undergo an RDA fragmentation accompanied by the transfer of two hydrogen atoms (RDA + 2H). Bicyclo[2.2.2]octene 5,6-diesters undergo both the RDA + H and RDA + 2H fragmentations, and the relative abundance of the resulting [dienophile + H]⁺ and [dienophile + 2H]⁺˙ ions is strongly affected by configuration.     

手性二环[3.3.0]辛-3-烯类化合物的合成

研究了5-(1-孟氧基)-3-溴-2(5H)-呋喃酮新手性源(1)与某些碳亲核试剂发生的串联不对称Michael加成/分子内亲核取代反应,反应中生成2个新的手性中心得到一般方法难以合成的光学纳二环[3.3.0]辛-3-烯类化合物.通过[α]、IR、UV、¹HNMR、¹³CNMR、MS、元素分析以及X射线四圆衍射等方法确定了手性二环[3.3.0]辛-3-稀类化合物化学结构和绝对构型.     

Diels-Alder reactions of fused pyran-2-ones with maleimides: efficient syntheses of benz[e]isoindoles and related systems

[reaction: see text] The Diels-Alder reaction of some substituted 5,6,7,8-tetrahydro-2H-1-benzopyran-2-ones (1a-f) with N-substituted maleimides (2a-c) leading to fused isoindole derivatives (5a-n, 7) or, in a few cases, to bridged double cycloadducts (fused bicyclo[2.2.2]octene derivatives) (6a-f) is presented. When X = CO, the first efficient, substituent-driven aromatization of an intermediary-formed cycloadduct was observed, resulting in substituted benz[e]isoindoles (5a-k). The same type of aromatization can also be achieved in an unprecedented catalysis with Rh/C.     

Proprietes des derives des tricyclo[6,n,0,02,7]trienes-2,4,6—IV : Reactivite des tricyclo[6,n,0,02,7]trienes-2,4,6 ols-1 en milieu acide

The action of toluene-p-sulphonic acid on tri- and tetracyclic benzocyclobutenols leads to the corresponding olefins. In some cases, after rearrangement derivatives of anti-2,7- benzobicyclo[3,2,1]octene are obtained. A mechanism is proposed for this rearrangement.     

Réductions chimique et électrochimique de benzopyranno-1 as-triazines

Electrochemical reduction of [1]benzopyranno[4,3-e]-as-triazinones gives 1,4-dihydro derivatives which can either rearrange into 4,4a-dihydro compounds or be reduced with ring contraction into benzopyranno-imidazolones. The reaction of Grignard reagents on benzopyrannotriazines leads to a reduction in –α position of the benzene ring (4,4a-dihydro). Electrochemical reduction gives the 1,4-dihydro derivative which rearrange into the 1,10a-dihydro compound. The 1,4-dihydro derivatives are reduced with triazine ring contraction to give benzopyrannoimidazoles. Dihydro-1,10a compounds can be reduced into imidazoles or into tetrahydro derivatives.     

Synthèse facile de dérivés du diphényl-2,4-aza-3-bicyclo[3.3.1]nonane et du diphényl-7,8-aza-8-bicyclo[4.3.1]décane

Facile synthesis of derivatives of 2,4-diphenyl-3-azabicyclo[3.3.1]nonane and 7,9-diphenyl-8-azabicyclo[4.3.1]decane The facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4-diphenyl-3-azabicyclo[3.3.1]nonanone and 7,9-diphenyl-8-azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.     

Synthèse et étude de modèles de NADH à noyaux accolés en série pyrrolo[2,3-b] et [3,2-b]pyridines

Pyrrolo[2,3-b] and [3,2-b]pyridines derivatives, precursors for annealated NADH models have been prepared. Several methods for building a pyridinic annealates ring have been used starting from 2- or 3-aminopyrrole. The corresponding dihydropyridine structure leads to highly reactive NADH models compounds and are very much more stable than common models.     

Diazabicycloalkanes with nitrogen atoms in bridgehead positions. 15. Reactions of benzo[b]-1,4-diazabicyclo[2.2.2]octene monoquaternary salt derivatives with nucleophilic reagents

Monoquaternary salt derivatives of benzo[b]-1,4-diazabicyclo[2.2.2]octene react with piperidine and sodium methoxide or 4-tert-butylthiophenoxide to give primarily N,N-disubstituted tetrahydroquinoxalines. Rate constants have been measured for these bimolecular reactions. Based on their levels of reactivity, these quaternary salts behave as typical alkylating agents.For communication 14, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 966–972, July, 1987.     

Spectrométrie de Masse D'hétérocycles Séléniés. III—Etude de la Fragmentation de Quelques Selenolo [2, 3-b] Pyridines

The mass spectra of thirteen selenolo[2,3-b]pyridine derivatives have been measured and compared with those of benzo[b]selenophene, quinoline and thieno[2,3-c]pyridine. The influence of diheteroatomic structure of the nucleus on the mechanism of fragmentation of the oxygenated substituents is discussed.     

Synthèse,réduction chimique et électrochimique de benzopyranno[1][4,3-e] et [3,4-e]pyrimido[1,2-b]-as-triazinones

From 9H-amino [l]benzopyranno-as-triazines 2 and 3 , [l]ben-zopyranno[4,3-e] or [3,4-e]pyrimido[l,2-b]-as-triazinones have been prepared by reaction with β-ketoesters. Chemical reduction of the compounds gives tetrahydro derivatives. By electrochemical reduction the dihydro compounds 14 and 15 were from-ed. The same dihydro derivatives were obtained with Grignard reagents.     

Synthesis of 2,6-dioxabicyclo[3.3.0]octenes by tandem ring-rearrangement/cross metathesis

A facile synthesis of stereodefined 2,6-dioxabicyclo[3.3.0]octene derivatives from the vinyl ether of endo-7-oxanorbornen-2-ol via tandem ring-opening/ring-closing(ring-rearrangement)/cross metathesis is reported.     

Thio-I ehromannones 5,8-disubstituées et synthèses dans la série du thiéno[4,3,2-de] thiochromanne

With the aim of obtaining the thieno[4,3,2-de] thiochromane structure, various 5,8-disubstituted derivatives of [1]thiochromanone have been synthesized. The structures of the compounds thus obtained and of the intermediates used in their syntheses were confirmed by nmr spectroscopy or by chemical procedures.     

Nouvelle méthode d'accès aux benzo[h]furo[3,2-c]quinoléines,analogues isostériques des benzo[c]phénanthridines

A convenient synthesis of the benzo[h]furo[3,2-c]quinoline ring is reported. Hydrogenation of dienic adducts 5 gives comppounds 6. Successive pyrolysis and alcaline hydrolysis of 6 provide diacids 9 which in the presence of anhydrous ammonium acetate and acetic acid undergoes intramolecular cyclisation to give benzo[h]furo[3,2-c]quinolone derivatives 12. The modulation of the 7-carboxy group and introduction of amino groups in the 6 position are then realized.     

Propriétés de la benzopyranno[1][2,3-b]quinoxalinone-12

Under basic conditions. [1]benzopyrano[2,3-b]quioxakin-12-one leads to 3-(i-hydroxybenzoy1)-1H-quinoxalin-2-one. This ketone reacts with hydroxylamine and phenylhydrazine to give the expected derivatives or those of [1]benzopyrano92,3-b]quinoxalin-12-one. The reduction of [1]benzopyrano[2,3-b]quinoxalin-12-one was unsucessful by chemical means. However, electrochemical reduction leads to a dihydropyrazine nucleus.     

First comprehensive investigation of Suzuki couplings of alkenyl nonaflates with aryl and alkenyl boronic acid derivatives by using classical conditions and microwave heating

Alkenyl nonaflates (nonafluorobutanesulfonates) are excellent substrates in a variety of palladium-catalysed coupling reactions. We herein demonstrate that bicyclic nonaflates generated from 8-heterobicyclo[3.2.1]octan-3-one derivatives can be coupled with aryl or alkenyl boronic acids in a very efficient manner. The resulting densely functionalised bicyclic skeletons are highly suitable for further synthetic elaboration. The thermal Suzuki couplings provided the expected products in moderate to good yields. Microwave (MW) irradiation dramatically shortened reaction times and gave superior results. Bisboronic ester 19 was also coupled with bicyclic nonaflates, for example, with 14, and double Suzuki-coupling products, such as 22, were isolated in good yields. We demonstrated the great synthetic potential of aryl-substituted 8-heterobicyclo[3.2.1]octene derivatives, such as 15, by the stereoselective conversion of this compound into highly substituted furanose 31 or substituted pyran derivative 33, which were obtained in short and efficient reaction sequences.     

The Effect of Onium Salt Additives on the Diels-Alder Reactions of a 1-Phenyl-1,2-dihydrophosphinine Oxide under Microwave Conditions

The microwave absorbing ability of toluene is increased in the presence of a slight amount (2–4 mg/3 mL) of quaternary ammonium or phosphonium salts. These additives somewhat accelerated the Diels-Alder reaction of 1-phenyl-1,2-dihydrophosphinine oxide 1 with N-phenylmaleimide and maleic acid anhydride to afford phosphabicyclo[2.2.2]octene derivatives.