Synthesis of tricyclo(5.2.1.04,10)decane-2,5,8-trione from deslongchamps's diketone

Tricyclo(5.2.1.0^4,10)decane-2,5,8-trione (1) has been synthesized by base-induced cyclization of intermediates of type A readily available from Deslongchamps's diketone 2.     

Stereoselective Synthesis of Tris-endo-tricyclo [5.2.1.04,10]decane-2,5,8-triamine

The title compound has been stereoscelectively obtained by a two-step process involving the catalytic hydrogenation of triketone 2 in the presnece of benzylamine with a partially deactivated catalyst.     

The Synthesis of 4,7-Bis(dialkylamino)tricyclo[5.2.1.04,10]deca-1(10),2,5,8-tetraenes and their Reduction with Alkali Metal

The synthesis and characterization of the novel 4,7-bis(dialkylamino)tricyclo[5.2.1.0^4,10]deca-1(10), 2,5,8-tetraenes 12 from 1,4,7-trihalotriquinacenes 8 and secondary amines is reported. The structural and electronic characteristics of these as well as the acepentalene dianion ( 3^2? ) and some related systems as determined by semiempirical (MNDO) calculations are discussed. Thereby, 3^2? should be a triply etheno-bridged trimethylenemethane dianion exhibiting Y-delocalization favored over the formation of a peripheral 10π-electronic system. Attempts directed towards the generation of 3^2? by reacting tetraenes 12 with Na led to the formation of tris(dialkylamino)triquinacenes 9 , presumably by a kind of reduction/disproportionation mechanism.     

Synthesis of Tricyclo [6.2.1.01,5]undecadiones via Intramolecular Photoaddition of 5-(1-Cyclopentenylmethyl)-3-alkoxy-2-cyclopentenones

Irradiation of the dienone methyl ether 3a furnished the unstable regioisomeric photoadducts 4a and 5a which on Lewis acid-catalyzed fragmentation afforded the tricyclic diketones 6,7 and 8 . The same mixture was obtained from the isobutyl ether 3b (Scheme 2).     

Synthesis and hydroboration/oxidation of tricyclo(5.2.1.04,10)dec-8-ene-2,5-dione(bis-acetal): new synthetic entry to tricyclo(5.2.1.04,10)decane-2, 5, 8-trione

Tricyclo(5.2.1.0^4,10)decane-2,5,8-trione (4) has been synthesized from the corresponding bis-acetal of the unsaturated diketone 20 by a hydroboration/oxidation/deprotection sequence.     

Attempted Synthesis of Tricyclo[3.3.2.024]DEC-2(4)-ENE

The synthesis of tricyclo[3.3.2.0^2,4]-dec-2(4)-ene (3) has been attempted using a route analogous to those previously developed for 1 and 2. Complications were encountered in the synthesis. The conformational problems of the larger polycyclic structures in the synthesis of 3 must be more difficult to overcome than the increased angle strain of the smaller rings when 1 or 2 are synthesized.     

Intramolecular Pauson-Khand reactions of alpha,beta-unsaturated esters and related electron-deficient olefins

The intramolecular Pauson-Khand (PK) reaction of a variety of electron-poor enynes having an ester, cyano, or phosphonate group at the olefin terminus is described. Depending on the reaction conditions and substitution at the enyne, their dicobalthexacarbonyl complexes led preferentially to the exocyclic 1,3-diene or to the PK cyclopentenone product. In general, the 1,3-diene was obtained as the major product under N-oxide-promoted conditions, while the PK product was selectively formed in refluxing acetonitrile.     

Synthesis of Phthalocyaninato Silicium Monooxide by Intramolecular Dehydration of Dihydroxo (Phthalocyaninato) Silicium

2,9,16,23-tetra-tetradecanophthalocyaninato silicium monooxide was first synthesized by the reaction of dihydroxo (2,9,16,23-tetra-tetradecano phthalocyaninato) silicium with NaOCH₃ The conversion was more than 90% and the selectivity was 100%.     

Intramolecular Pauson-Khand reactions of methylenecyclopropane and bicyclopropylidene derivatives as an approach to spiro(cyclopropanebicyclo[n.3.0]alkenones)

The trimethylsilyl-protected enynes 9a-c and 14a,b with alkynyl substituents on the three-membered ring or on the double bond of a methylenecyclopropane or a bicyclopropylidene moiety were prepared in two steps from the alcohols 6a-c and 12a,b, respectively, by conversion to the iodides and their coupling with lithium (trimethylsilyl)acetylide (8) in 38-73% overall yields. The bicyclopropylidene derivative 9d was synthesized in 49% yield directly from bicyclopropylidene (3) by lithiation followed by coupling with (5-iodopent-1-ynyl)trimethylsilane (11). Enynes 9b-d were protiodesilylated by treatment with K2CO3 in methanol to give the corresponding unprotected enynes 10b-d in 53, 74 and 94% yield, respectively. Enynes 17a-c with a carbonyl group adjacent to the acetylenic moiety were synthesized from oxo derivatives 15a-c by Wittig olefination followed by coupling with 8 in 47, 18 and 12% overall yield, respectively. Pauson-Khand reactions of the methylenecyclopropane derivatives with a substituent on the ring (9a,b and 10a) as well as on the double bond (14a,b and their in situ prepared protiodesilylated analogues) proceeded smoothly by stirring of the corresponding enyne with [Co2(CO)8] in dichloromethane at ambient temperature followed by treatment of the formed complexes with trimethylamine N-oxide under an oxygen atmosphere at -78 degrees C to give tricyclic or spirocyclopropanated bicyclic enones 18a,b, 19a, 20a,b, 21a,b in good yields. Alkynylbicyclopropylidene derivatives 9c,d and 10c,d formed the corresponding cobalt complexes at -78 to -20 degrees C. Treatment of the latter with N-methylmorpholine N-oxide under an argon atmosphere at -20 degrees C gave the spirocyclopropanated tricyclic enones 18c, 19c and 18d in 31-45% yields. The structure of 19c was proved by X-ray crystal structure analysis. The cyclization of enynones 17a-c in MeCN at 80 degrees C gave the spirocyclopropanated bicyclic diketones 22a-c in 38-65% yields. Intramolecular PKRs of the enynes 25a,d with a chiral auxiliary adjacent to the triple bond gave the corresponding products 26a,d in 70 and 79% yield, respectively, as 5:1 and 8:1 mixtures of diastereomers, respectively. Addition of lithium dimethylcuprate or higher order cuprates to the double bond of the former furnished bridgehead-substituted bicyclo[3.3.0]octanones 27a-c in 57-86% yields. Protiodesilylation of 27a followed by acetal cleavage gave the enantiomerically pure spirocyclopropanated bicyclo[3.3.0]octanedione (1R,5R)- 29a with [alpha]D(20)=-148 (c=1.0 in CHCl3) in 55% overall yield.     

Tricyclo[7.2.1.02,7]dodec-2(7)-en-12-one. Synthesis and Some Reactions

Tricyclo[7.2.1.02,7]dodec-2(7)-en-12-one was synthesized by dehydration of the corresponding hydroxy ketone and was brought into the Leuckart reaction. The resulting N-tricyclo[7.2.1.0^2,7]dodec-2(7)-en- 12-ylformamide was hydrolyzed to 12-aminotricyclo[7.2.1.02,7]dodec-2(7)-ene and was converted into 2,7-epoxy derivative. The structure of the latter was determined by X-ray analysis. Hydrolysis of the amide group gave 12-amino-2,7-epoxytricyclo[7.2.1.02,7]dodecane. The stereochemistry of hydroamination of the bridging carbonyl group is discussed.     

一种改进方法合成六（4－硝基酚氧）环三磷腈

报道合成六（4-硝基酚氧）环三磷腈的一种改进方法,该法大大缩短了反应时 间（约1.5 h）,简化了操作。产物经红外、核磁氢谱和磷谱的分析、元素分析以 及差示扫描量热分析。     

Synthesis of a ketone analogue of biotin via the intramolecular Pauson-Khand reaction

We report an improved synthesis of 5-(5-oxohexahydrocyclopenta[c]thiophen-1-yl)pentanoic acid (ketone biotin, 1) based on the intramolecular Pauson-Khand cyclization. The synthesis proceeds in eight steps and in 2.7% overall yield from cyclohexene.     

Intramolecular alkene hydroaminations catalyzed by a bis(thiophosphinic amidate) Zr(IV) complex

A neutral Zr(IV) complex has been shown to be an effective precatalyst for intramolecular alkene hydroaminations that provide cyclic amines in good to excellent yields.     

Synthesis of pyridine derivatives. Intramolecular cyclization of δ-oxonitriles (Review)

Literature data on cyclization of 6- oxonitriles to pyridine derivatives are analyzed and generalized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 735–759, June, 1995. Original article submitted September 28, 1993.