Synthesis and Crystal Structure of 2,6,8,12-Tetraacetyl- 2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05,9.03,11]dodecane

1 INTRODUCTION Hexanitrohexaazaisowurtzitane (HNIW or CL-20),the fourth generation in energetics, is the most power-ful explosive available for military applications inboth plastic bonded explosive (PBX) compositionsand propellant. To date, a number of nitrolyzable pre-cursors to CL-20 have been investigated, includingisowurtzitane cages substituted with acetyl, formyland nitroso groups and partly unsubstituted cages.Only the synthetic route of CL-20 using 2,6,8,12-te-traacetyl-2,4,6…     

Tricyclo[4.2.2.22,5] dodecane and Tricyclo [4.2.2.12,5]undecane. Preliminary communication

A synthesis of tricyclo [4.2.2.2^2,5]dodecane ( 19 ), a novel tricyclic C₁₂H₂₀ compound, is described. The key intermediate ketone 13 was prepared either from the C₁₀-photodimer 1 of cyclopentadienone or the C₁₁-cycloaddition products 11 and 12 . 13 was also transformed to tricyclo [4.2.2.1^2,5]undecane ( 8 ).     

吸热型碳氢燃料五环[6.3.1.02,7.03,5.09,11]十二烷的催化合成

吸热型碳氢燃料是为解决高超音速飞行器冷却难题而研制的一类新型燃料[1].其最突出的优点是作为性能优良燃料的同时,还能满足飞行器的冷却要求,可减小飞行器的体积和质量,提高飞行速度,是高超音速飞行器的理想燃料.其冷却及燃烧原理是:大分子碳氢燃料在进入燃烧室前吸收飞行系统产生的热量气化、再裂解为小分子,产物进入燃烧室燃烧并释放出吸收的热量,从而在对系统冷却的同时提高了能源的利用率,减少了高超音速飞行器的负载,满足了燃烧室壁面和机身温度控制等要求.因此,吸热型碳氢燃料已成为各国研发的热点,但目前研究多限于原油调配燃料的催化裂解和脱氢,对新燃料的合成报道较少[2,3].……     

Synthesis of 3,11-Dioxatetracyclo[6.3.0.02,6.05,9]undecanes and 3,5,7-Trioxapentacyclo[7.2.1.02,8.04,11.06,10]dodecane

The synthesis of 3,11-dioxatetracyclo[6.3.0.0^2,6.0^5,9]undecanes has been accomplished from furans in a short sequence by iodine-induced cyclization reaction. The application of iodine-induced cyclization reaction for the synthesis of 3,5,7-trioxapentacyclo[7.2.1.0^2,8.0^4,11.0^6,10]dodecane itself was also demonstrated.     

3-Oxawurtzitane (3-Oxatetracyclo[5.3.1.12,604,9]dodecane)

A synthesis of 3-oxawurtzitane (3-oxatetracyclo[5.3.1.1^2,60^4,9]dodecane) ( 8 ) is described.     

Biosynthesis of a Tricyclo[6.2.2.02,7]dodecane System by a Berberine Bridge Enzyme-Like Aldolase

The aldol reaction is one of the most fundamental stereocontrolled carbon–carbon bond-forming reactions and is mainly catalyzed by aldolases in nature. Despite the fact that the aldol reaction has been widely proposed to be involved in fungal secondary metabolite biosynthesis, a dedicated aldolase that catalyzes stereoselective aldol reactions has only rarely been reported in fungi. Herein, we activated a cryptic polyketide biosynthetic gene cluster that was upregulated in the fungal wheat pathogen Parastagonospora nodorum during plant infection; this resulted in the production of the phytotoxic stemphyloxin II ( 1 ). Through heterologous reconstruction of the biosynthetic pathway and in vitro assay by using cell-free lysate from Aspergillus nidulans, we demonstrated that a berberine bridge enzyme (BBE)-like protein SthB catalyzes an intramolecular aldol reaction to establish the bridged tricyclo[6.2.2.0^2,7]dodecane skeleton in the post-assembly tailoring step. The characterization of SthB as an aldolase enriches the catalytic toolbox of classic reactions and the functional diversities of the BBE superfamily of enzymes.     

Synthesis and properties of 1,4,9-triazaspiro[5,5]undecane and 3,7,11-triazaspiro[5,6]dodecane

Bromination of 1-methylpiperidine-4-carboxaldehyde gave 4-bromo-1-methylpiperidine-4-carboxaldehyde hydrobromide which was used to synthesize 1,4,9-triazaspiro[5,5]undecane and 3,7,11-triazaspiro[5,6]dodecane. Cyanoethylation and alkylation with various alkyl halides gave their mono- and di-substituted derivatives. The side chain nitrile group was reduced and the hydrazide was obtained from the ester analog.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1673–1676, December, 1986.     

Nitrolysis of 2,6,8,12-tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.03,11.05,9]dodecane

Russian Chemical Bulletin - Nitrolysis of 2,6,8,12-tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaazatetracyclo-[5.5.0.03,11.05,9]dodecane results in the substitution of benzyl groups by the nitro...     

Synthesis of 3,5,7-Trioxapentacyclo[7.2.1.02,8.04,11.06,10]dodecane. A Novel Diacetal Trioxa-Cage

3,5,7-Trioxapentacyclo[7.2.1.0^2,8.0^4,11.0^6,10]dodecane, the parent compound of novel diacetal trioxa-cages, was synthesized from maleic anhydride cyclopentadiene adduct 1 by a four-step sequence. Attempts for the synthesis of monoaza dioxa-cage 12 failed. Ozonolysis of compound 9 in CH₂Cl₂-EtOH(1:1) at ?78°C followed by reduction with Me₂S gave 13 in 65% yield.     

Domino Reaction for the Synthesis of Highly Functionalized Triazatricyclo[6.2.2.01,6]dodecane

A simple and highly efficient protocol has been developed for the synthesis of triazatricyclo[6.2.2.0^1,6]dodecane-9,12-dione (TATCD) derivatives. Use of metal hydroxide catalyst in the presence of protic solvent plays a key role in these reaction transformations. Mechanistic studies specify that the proposed mechanism proceeds only via aldol reaction, condensation, cyclization, and dehydration to form the desired product. This current protocol provides several advantages such as use of a readily available precursor, consumption of less energy, short reaction time, moderate to good yields, and convenient workup.     

Chemical Transformations of 4,6-Dimethyl-2β-hydroxy-8-oxo-3,5,7-trioxatetracyclo[7.2.1.04,11.06,10]dodecane

Reactions of 4,6-dimethyl-2β-hydroxy-8-oxo-3,5,7-trioxatetracyclo-[7.2.1.0.^4,11.0^6,10]dodecane 1 with nucleophiles have been studied. Reaction of 1 with alcohols, triethylsilane, allyltrimethylsilane, and methylthiotrimethylsilane in CH₂Cl₂ in the presence of TiCL₄, gave the substitution products 2,7a, 7b, and 7c in 80-90% yields. The substitution reaction took place chemoselectively on the hemiacetal group of I. Reaction of 1 with cyanotrimethylsilane in CH₂C1₂ in the presence of TiCL₄, gave compound 8 and the rearranged product 9. The structure of 9 was proven by X-ray analysis.     

Synthesis and Structure of Ba[ZrN2] and Ba2[NbN3]

Ba₃N₂ reacts at 950°C under pure N₂ with Zr to yield dark red, air-sensitive Ba[ZrN₂]. This new compound crystallizes in the tetragonal space group P4/nmm with a = 416.10(2), c = 839.2(1) pm and Z = 2. The crystal structure was solved and refined using X-ray and neutron powder diffraction data. In the nitrido zirconate [ZrN₂]^2? the Zr atoms exhibit a square-pyramidal coordination by five N atoms at distances of 201(3) and 220.2(2) pm. The pyramids share all the edges in the basal plane to form layers parallel to (001) with their apices alternately pointing up and down. The Ba²⁺ cations are integrated into these layers at the levels of the pyramidal apices. The structure can be interpreted as a stuffed PbFCl type. Ba₂[NbN₃] is formed by the reaction of Ba₃N₂ and NbN or of Ba and Nb at 1 000°C under N₂. Isostructural to Ba₂[TaN₃] it crystallizes in the monoclinic space group C2/c with a = 613.2(3), b = 1 176.8(3), c = 1 322.9(4) pm, β = 91.65(2)°, Z = 8. The nitrido niobate anions form chains of corner sharing NbN₄ tetrahedra with distances Nb? N between 188(1) and 199.9(9) pm.     

Synthesis of tricyclo[6.2.2.0]dpdecane and tricyclo[6.3.1.0]dodecane ring systems involving intramolecular cyclisation of diazomethyl ketones

2,8-Dimethyltricyclo[6.2.2.0^1,6]dodeca-2,5-diene-4,9-dione ( ), 2,9-dimethyltricyclo [6.3.1.0^1,6]dodeca-2,5-diene-4,10-dione ( ) and 2-methyltricyclo[6.3.1.0^1,6]dodeca-2,5-diene-4,10-dione ( ) have been synthesised for entry into the ring systems of a few tetracyclic diterpenes.