4-Aminobicyclo[2.2.2]octanone Derivatives with Antiplasmodial and Antitrypanosomal Activities

Summary. 4-Aminobicyclo[2.2.2]octanones were converted to their N-oxides and to 4-aminobicyclo[2.2.2]octanes. Furthermore, the 6,7-bis-(4-methoxyphenyl) analogues were synthesized. All products were screened for their activities against Trypanosoma b. rhodesiense and Plasmodium falciparum. The pharmacological results were compared with those of formerly tested bicyclo[2.2.2]octanones and bicyclo[2.2.2]octanols. Structure-activity relationships are discussed.Received April 8, 2003; accepted April 14, 2003 Published online September 25, 2003     

4-Aminobicyclo[2.2.2]octanone Derivatives with Antiprotozoal Activities

 4-Aminobicyclo[2.2.2]octanones which were prepared in one-pot-reactions from benzylidene acetone and dialkylammonium rhodanides were reduced stereoselectively to their corresponding alcohols. The activities of the bicyclic compounds against causative organisms of tropical deseases were examined. The 4-aminobicyclo[2.2.2]octan-2-ols were in general more active against Trypanosoma b. rhodesiense and Plasmodium falciparum than the corresponding keto compounds.     

Hydrazones and new Oximes of 4-Aminobicyclo[2.2.2]octanones and their Antiprotozoal Activities

Summary. 4-Aminobicyclo[2.2.2]octan-2-ones and -ols showed activity against the causative organisms of East African sleeping sickness and Malaria tropica. Several imino derivatives of the ketones were more active. Now hydrazono analogues and 3-hydroximino derivatives of the ketones and alcohols were synthesized. The structures of the obtained isomers were elucidated by NMR spectroscopy. A single phenylhydrazone exhibited quite good antitrypanosomal activity in the range of already known imino analogues.     

4-Aminobicyclo[2.2.2]octanone Derivatives with Antiplasmodial and Antitrypanosomal Activities

4-Aminobicyclo[2.2.2]octanones were converted to their N-oxides and to 4-aminobicyclo[2.2.2]octanes. Furthermore, the 6,7-bis-(4-methoxyphenyl) analogues were synthesized. All products were screened for their activities against Trypanosoma b. rhodesiense and Plasmodium falciparum. The pharmacological results were compared with those of formerly tested bicyclo[2.2.2]octanones and bicyclo[2.2.2]octanols. Structure-activity relationships are discussed.     

Thermal behaviour of some dibenzobicyclo[2.2.2]octane derivatives

A number of dibenzobicyclo[2.2.2]octane derivatives have been studied due to the interest of such compounds as ligands for coordination compounds with potential biological activity. Their thermal behaviour has been analyzed in order to find out more information about their fragmentation. A connection between the bridge substituents and the fragmentation process has been observed.     

Structural Requirements for the Antiprotozoal Activity of 4-Aminobicyclo[2.2.2]octan-2-ols

Summary. Several 4-aminobicyclo[2.2.2]octan-2-ones and -ols were synthesized using different pathways. The new compounds were investigated for their activity against Trypanosoma b. rhodesiense, the causative organism of East African sleeping sickness and Plasmodium falciparum the protozoan parasite which causes Malaria tropica. The results are compared to the activities of known compounds and the influence of the substitution of the bicyclo[2.2.2]octane skeleton on the biological activities is discussed.     

Retro-Diels-Alder reaction using bicyclo[2.2.2]octatriene-fused pyrrole during porphyrin synthesis

Porphyrin synthesis using 4,7-etheno-4,7-dihydro-2H-isoindole and tripyrranedicarbaldehyde gave a porphyrin derivative bearing no bicyclo[2.2.2]octatriene moiety as well as the targeted bicyclo[2.2.2]octatriene-fused porphyrin.     

Concise synthesis of the core bicyclo[2.2.2]diazaoctane ring common to asperparaline, paraherquamide, and stephacidin alkaloids

A versatile synthesis of the bicyclo[2.2.2]diazaoctane core structure of asperparaline, brevianamide, paraherquamide, and stephacidin natural products is demonstrated. This convergent synthesis relies on an intramolecular hetero Diels-Alder reaction to construct the key tetracycle from a diketopiperazine derived azadiene; which in turn was formed from prolinamide and a pyruvic acid derivative. The stereochemical outcome of the Diels-Alder reaction was found to favor the brevianamide stereochemistry.     

1,4-二氮杂双环[2.2.2]辛烷催化的有机化学反应

综述了有机小分子催化剂1,4-二氮杂双环[2.2.2]辛烷(DABCO)在有机合成反应中的应用与发展。这种有机小分子催化的反应大多数条件温和、操作简单;相对过渡金属而言,对环境友好;在一定条件下,这种催化剂可以回收再利用。     

Mild and efficient Sonogashira couplings of 8-oxa- and 8-thiabicyclo[3.2.1]octanone derived alkenyl nonaflates

We demonstrate in this report that bicyclic alkenyl nonaflates (nonafluorobutanesulfonates) generated from 8-heterobicyclo[3.2.1]octan-3-one derivatives are excellent substrates for Sonogashira couplings with alkynes. Employing CuI, Pd(OAc)₂, PPh₃ in DMF/i-Pr₂NH as standard reagents structurally diverse bicyclic nonaflates were coupled with phenyl acetylene in generally high yields. Particularly efficient are transformations of precursors 16, 18, and 20 bearing methyl groups at the bridgehead carbons, which furnished the expected enynes 17, 19, and 21 in approximately 90% yield. With respect to the alkyne component the scope of this palladium-catalyzed reaction seems also to be fairly broad. Thus, trimethylsilyl acetylene and propargyl alcohol could also be used, affording coupling products 22, 23, and 25 with high efficacy. The protocol of Grieco was applied to induce a domino coupling of tricyclic alkenyl nonaflate 14 with trimethylsilyl acetylene affording product 26 in moderate yield and as 1:1 mixture of the expected two diastereomers.     

Synthesis of a pericosine analogue with a bicyclo[2.2.2]octene skeleton

A new analogue of the antitumor pericosines possessing a bicyclo[2.2.2]octene skeleton has been synthesized from methyl gallate using oxidative dearomatization and regio- and diastereoselective Diels-Alder reaction as the key steps.     

Organic reactions catalyzed by 1, 4-diazabicyclo [2.2.2] octane (DABCO)

The organic reactions catalyzed by 1, 4-diazabicyclo [2.2.2] octane (DABCO) are reviewed. Most of the reactions start conveniently from available substrate and proceed under mild conditions. The reactions are environmentally friendly and the catalyst can be recycled in some cases. The perspectives on DABCO-catalyzed reactions are pointed out. __________ Translated from Chemistry online, 2007, 70(10): 759–765 [译自: 化学通报]     

Synthesis and characterization of poly(benzazoles) containing the bicyclo[2.2.2]octane moiety

Poly(benzobisoxazoles) (PBOs), poly(benzobisthiazoles) (PBTs) and copolymers thereof containing the 2,5-dihydroxybicyclo[2.2.2]octane moiety have been prepared and studied. The homopolymers were synthesized by the polycondensation of 2,5-dihydroxybicyclo[2.2.2]octane-1,4-dicarboxylic acid with 4,6-diamino-1,3-benzenediol dihydrochloride or 2,5-diamino-1,4-benzenedithiol dihydrochloride in poly(phosphoric acid). Random and block copolymers (PBO–PBT) were also prepared. The polymers were characterized by solubility, X-ray diffraction, spectroscopy (infrared and solid-state ¹³C nuclear magnetic resonance), and thermal analysis such as differential scanning calorimetry and thermogravimetric analysis. Thermogravimetric analysis showed thermal stability of the polymers above 375°C in air and under argon atmosphere. The polymers exhibited high resistance to organic and inorganic solvents. The polymers were converted to the more stable aromatic polymers via dehydration and retro Diels–Alder reactions of the 2,5-dihydroxybicyclo[2.2.2]octyl moiety by pyrolysis. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 277–281, 1998     

Formation of Tetraacetal Oxa-Cages and Convex Oxa-Cages on Ozonolysis of Bicyclo[2.2.2] Octenes

Tetraacetal oxa-cage compounds 5a and 5b and convex oxa-cage compounds 7a and 8b are synthesized in a short sequence. Ozonolysis of endo adducts 2a and 2b in dichloromethane at ?78 °C followed by reduction with dimethylsulfide gave tetraacetal oxa-cages 5a and 5b in 35% yields respectively. Ozonolysis of 2a in dichloromethane at ?78 °C followed by treatment with triethylamine gave the convex oxa-cage 7a in 34% yield. These results support an acid-base proton transfer between the final ozonides and the base. The reasons that these oxa-cage compounds formed in low yields are discussed. The synthesis of tetraacetal oxa-cage 14, possessing aromatic substitutents directly on the skeleton of the oxa-cage, is accomplished.     

An unexpected palladium-catalyzed cyclization of bis-hydroxy allylic alcohols to dioxabicyclo[2.2.2]octanes

The palladium(II)-catalyzed cyclization of bis-hydroxy allylic alcohols afforded quantitatively a mixture of (3-alkyl-5-vinyltetrahydrofuran-3-yl)methanol and 4-alkyl-1-methyl-2,6-dioxabicyclo[2.2.2]octane.     

Hydrazones and new Oximes of 4-Aminobicyclo[2.2.2]octanones and their Antiprotozoal Activities

4-Aminobicyclo[2.2.2]octan-2-ones and -ols showed activity against the causative organisms of East African sleeping sickness and Malaria tropica. Several imino derivatives of the ketones were more active. Now hydrazono analogues and 3-hydroximino derivatives of the ketones and alcohols were synthesized. The structures of the obtained isomers were elucidated by NMR spectroscopy. A single phenylhydrazone exhibited quite good antitrypanosomal activity in the range of already known imino analogues.     

1-氮杂环[2.2.2]辛烷的高效合成

将4-（2-羟乙基）哌啶蒸汽在425 ℃下通过CNM-3型固体酸催化剂进行分子内脱水反应,一步合成了目的产物1-氮杂环[2.2.2]辛烷（奎宁环）,4 h内25 g 4-（2-羟乙基）哌啶蒸汽单程收率可达76.8%,最高收率84.3%。 该方法原料易得,适合于奎宁环的工业化制备。     

Cycloaddition between electron deficient partners: an efficient regio- and stereoselective synthesis of functionalised bicyclo[2.2.2]octenones. A tandem alkylation, stereochemical inversion and aldol condensation

A novel one step regio- and stereoselective synthesis of functionalised bicyclo[2.2.2]octenones from readily available aromatic precursors is described. The methodology involved in situ generation of reactive spiroepoxycyclohexadienones and π^4s+π^2s cycloaddition with methyl vinyl ketone. Study on π-facial alkylation that led to the formation of homobrendane derivatives as a result of stereochemical inversion and aldol condensation in tandem, is also presented. The crystal structure of 6-acetyl-1-methoxy-bicyclo[2.2.2]oct-7-en-2-one-spiro[3,2′]oxirane and 3-methoxy-4,6,9-trimethyltricyclo[4.3.1.0^3,7]decan-8-en-5-one-spiro[2,2′]oxirane is also reported.     

Cubane,Bicyclo[1.1.1]pentane and Bicyclo[2.2.2]octane: Impact and Thermal Sensitiveness of Carboxyl-, Hydroxymethyl- and Iodo-substituents

With the burgeoning interest in cage motifs for bioactive molecule discovery, and the recent disclosure of 1,4-cubane-dicarboxylic acid impact sensitivity, more research into the safety profiles of cage scaffolds is required. Therefore, the impact sensitivity and thermal decomposition behavior of judiciously selected starting materials and synthetic intermediates of cubane, bicyclo[1.1.1]pentane (BCP), and bicyclo[2.2.2]octane (BCO) were evaluated via hammer test and sealed cell differential scanning calorimetry, respectively. Iodo-substituted systems were found to be more impact sensitive, whereas hydroxymethyl substitution led to more rapid thermodecomposition. Cubane was more likely to be impact sensitive with these substituents, followed by BCP, whereas all BCOs were unresponsive. The majority of derivatives were placed substantially above Yoshida thresholds—a computational indicator of sensitivity.     

An efficient synthesis of conjugation-expanded carba- and azuliporphyrins using a bicyclo[2.2.2]octadiene-fused tripyrrane

A bicyclo[2.2.2]octadiene-fused tripyrrane was synthesized as a first versatile reagent for the preparation of π-expanded heteroporphyrins. The reaction of the tripyrrane with 1,3-diformylindene and azulene-1,3-dicarbaldehyde afforded the corresponding heteroporphyrins, which were easily converted into tetrabenzocarbaporphyrin and tribenzoazuliporphyrin by retro Diels-Alder reaction.