Stereoselective diels-alder reactions between 9-alkyl-1,4-dihydronaphthalen-1,4-imines and 2-alkylisoindoles

The Diels-Alder reaction between 9-alkyl-1,4-dihydronaphthalen-1,4-imines ($\text{1}$) and 2-alkylisoindoles ($\text{2}$) occurs in refluxing xylene to give exclusively the exo-endo cyclo-adducts $\text{3}$ ($\text{D}$).     

Stereodynamics of 9,11-Diphenyl-10-azatetracyclo[6.3.0.0.(4,11)0.(5,9)]undecanes. Highly Restricted Nitrogen Inversion and Isolated Phenyl Rotation. X-ray Crystallographic, Dynamic NMR, and Molecular Mechanics Studies

The (1)H NMR spectra of 10-benzyl-9,11-diphenyl-10-azatetracyclo[6.3.0.0.(4,11)0.(5,9)]undecane (BnPh(2)()) and 10-methyl-9,11-diphenyl-10-azatetracyclo[6.3.0.0.(4,11)0.(5,9)]undecane (MePh(2)()) decoalesce due to slowing inversion at nitrogen and to slowing isolated bridgehead phenyl rotation. The high nitrogen inversion barriers in MePh(2)() (DeltaG() = 12.2 +/- 0.1 kcal/mol at 250 K) and BnPh(2)() (DeltaG() = 10.6 +/- 0.1 kcal/mol at 215 K) are typical of tertiary amines in which at least one C-N-C bond angle is constrained to a small value. Compared to the minuscule rotation barriers about sp(2)-sp(3) carbon-carbon bonds in simple molecular systems, the bridgehead phenyl rotation barriers in MePh(2)() (DeltaG() = 9.8 +/- 0.1 kcal/mol at 210 K) and BnPh(2)() (DeltaG() = 9.8 +/- 0.1 kcal/mol at 210 K) are unusually high. Molecular mechanics calculations (MMX force field) suggest that the origin of the high phenyl rotation barriers lies in the close passage of an o-phenyl proton and a methyl (or benzylmethylene) proton in the transition state. BnPh(2)() crystallized from hexane as white needles in the monoclinic system Pn. Unit cell dimensions are as follows: a = 12.198(1) ?, b = 6.1399(6) ?, c = 14.938(2) ?, beta = 107.470(4) degrees, V = 1067.1(2) ?(3), Z = 2. In the crystal molecular structure, the imine bridge CNC bond angle in BnPh(2)() is constrained to a small value (96 degrees ). The benzylic phenyl group is oriented gauche to the nitrogen lone pair.     

Regioselective ortho lithiation of halopyridines

Regioselective ortho lithiation of 2-, 3-, and 4-halopyridines is achieved with lithium diisopropylamide (?78°, tetrahydrofuran) to afford, upon quenching with electrophilic reagents, 2,3- and 3,4-disubstituted pyridines in good to excellent yield.     

An efficient synthesis of 4-(phenylsulfonyl)-4H-furo[3,4-b]indoles

The fused heterocycle 4-(phenylsulfonyl)-4H-furo[3,4-b]indole, which is an indole-2,3-quinodimethane synthetic analogue, is prepared in five steps from indole in 46% yield. A similar sequence is used to synthesize C-3 derivatives (3-methyl, 3-phenyl, and 3-heptyl). Thus, indole-3-carbaldehyde (1) is protected as the N-phenylsulfonyl derivative 2 and converted to the ethylene acetal 6. Lithiation at C-2 followed by treatment with an aldehyde affords the expected hydroxy acetals 7 and 8. Exposure to acid effects cyclization to the furoindoles 5 and 9. Furthermore, C-1 lithiation of furo[3,4-b]indole 9c followed by treatment with methyl iodide affords disubstituted furo[3,4-b]indole 10.     

Synthesis of a furano abietane cyano enone—A new scaffold for biological exploration

A six step synthesis of furano abietane cyano enone 12 is described, in which the key step is a palladium-catalyzed intramolecular Heck reaction of bromo 3-phenoxyacrylate 17, prepared from enone phenol 13 in high yield.     

The Atlas power-flow system-a status report

Atlas is a high-energy, pulsed-power facility under development to study materials properties and hydrodynamics under extreme conditions. Atlas will implode heavy liner loads (m ~ 45 gm) with a peak current of 27-32 MA delivered in 4 μs, and it is energized by 96, 240-kV Marx generators storing a total of 23 MJ. The power-flow system transports current from the Marx generators to the load. It includes a load protection switch to protect the load in case of a prefire; 24 oil-insulated, vertically oriented, radially converging, triplate transmission lines; a transition region that couples the transmission lines to the power-flow channel; and a radially converging, dielectric-insulated, horizontal and conical, power-flow channel. Proposed experiments, the design of the power-flow system, test results, and status are presented     

Interpolatory inner product quadrature formulas

The problem of obtaining quadrature formulas which approximate integrals of the product of two functions with a certain weight function, is considered. In previous work, the possibility of approximating both functions by an interpolating polynomial was examined. This approach is extended to a more general setting. A consequence of this is that the computational advantages and inherent flexibility of Inner Product Quadrature Formulas become apparent. A simple and efficient technique for obtaining such formulas is given. The question of approximating integrals involving the product of more than two functions is also discussed.     

Inner product quadrature formulas exact on maximal product spaces of functions

This work extends and complements earlier work of the author [1]. An Inner Product Quadrature Formula (I P Q F) is used when approximating the definite integral of the product of two (or more) funcitons, i.e. σ_?1¹w(x) f(x) g(x) dx, where w is a weight function. The functions f and g are approximated by interpolatory functions f_φ? span φ_{ii = 0}^γ, g_ψ? span ψj_{j = 0}^δ, and the integral σ_?1¹w(x)f_φ(x)g_ψ (x) dx is evaluated exactly. Maximal values which the numbers γ and δ may take are investigated. Numerical examples of I P Q F are given. Also, the applicaitons of I P Q F in higher dimensions are commented on.     

A convenient preparation of indoline

An efficient method for chemically reducing indole to indoline using zinc dust and 85% phosphoric acid is described. 2, 3-Dimethylindole, 1,2,3, 4-tetrahydrocarbazole and N-methyl-l,2,3,4-tetrahydrocarbazole are also reduced to the corresponding dihydroindoles in somewhat lower yields. Unlike earlier acid-metal reductions of indole little or no polymerization is observed.     

Synthesis of bisindolylmaleimides related to GF109203x and their efficient conversion to the bioactive indolocarbazoles

From a structure-activity relationship perspective, the new indolocarbazoles 11 and 12 have been synthesized and evaluated biologically as novel Chk1 inhibitors. Compounds 11 and 12 were synthesized in high yield from indole via bisindolylmaleimides 18 and 24.