A model for the synthesis of naturally occurring benzisochromenequinones

1,3-Dimethylbenzisochromene-5,10-quinone 14 is obtained in good yield when 2-(1′-hydroxyethyl)-3-prop-2″-enyl-1,4-naphthoquinone 13 is treated briefly with bisacetonitriledichloropalladium(II) in solution in dichloromethane at room temperature

Proton magnetic resonance and polarographic studies of some aminated naphthoquinones

Variable temperature n.m.r. and polarographic measurements have been performed on a series of cyclic secondary aminonaphthoquinones. The results indicate that ring strain is not the only factor which would explain the order of effective electron donation by the various amines to the quinone nucleus

Trifluoroacetylation of Oxygenated Naphthalenes. Synthesis of some Naphtho[2,3 c]pyran 5,10 quinones

Trifluoroacetic anhydride is shown to acylate 1,4,5-tri- and 1.4.5.7-tetramethoxynaphthalene, the former at C(3) or C(8), and the latter at C(8) exclusively. The same reagent also acylates 1-napththol and its 4,8-dialkoxy- and 4,6,8-triatkoxyderivatives to give ortto-trifluoroacetylnaphthols tn good yield. Cerium(IV) ammonium nitrate oxidation of the alkoxynaphthols gives the corresponding 2(1,1-dihydroxy-2- trifluoroethyl)-1 Anaphthoquinones. These quinones undergo hydroxypentylation of the quinonoid nucleus with 3- hydroxyhexanoic acid to give naphthol[2,3-c]pyran-5,10- quinones

Gravitational lensing by p-branes

The scattering of R-R gauge bosons off of Dirichlet p-branes is computed to leading order in the string coupling. The results are qualitatively similar to those found in the scattering of massless NS-NS bosons: all p-branes with p >= 0 exhibit stringy properties, in particular the Regge behavior. Both the R-R and NS-NS scattering amplitudes agree in the limit of small momentum transfer with scattering off the extremal R-R charged p-brane solutions found in the low-energy supergravities. We interpret this as evidence that Dirichlet-branes are an exact world-sheet description of the extremal p-branes. The -1-brane (D-instanton) is a special object which, unlike all other Dirichlet-branes, exhibits point-like behavior. We find the R-R charged instanton solution to type IIB supergravity and confirm that the field theoretic scattering off of this solution miraculously reproduces the full stringy calculation. As an aside, we include a discussion of the entropy of non-extremal black holes in ten dimensions, produced by exciting the 0-brane. We show that, for large black holes, the entropy grows linearly with the black hole mass.Comment: LaTeX, 18 pages, 1 figure, uses psfig.sty, available from http://xxx.lanl.gov/ftp/hep-th/papers/macros/psfig.sty Final version to appear in Nuclear Physics

first isolation of acetovanillone and piceol from crinum buphanoides and crinum graminicola i verd amaryllidaceae

Screening of three native South African Amaryllidaceae bulbs, aimed at finding new metabolites for their promising biological activities, lead to the initial discovery of two interesting non-alkaloid compounds viz., acetovanillone 1 (also known as apocynin) and 4-hydroxyacetophenone 2 (also named piceol) isolated from Crinum buphonoides, while only the former was isolated from Crinum graminicola. This is the first time that acetovanillone 1 and piceol 2 were isolated from C. graminicola and C. buphanoides, respectively. Acetovanillone 1 was recently reported as a metabolite of Boophane disticha (L.f.), another South Africa Amaryllidacea species

D3-branes on the Coulomb branch and instantons

The relative coefficients of higher derivative interactions of the IIB effective action of the form C^4, (D F_5)^4, F_5^8, ... (where C is the Weyl tensor and F_5 is the five-form field strength) are motivated by supersymmetry arguments. It is shown that the classical supergravity solution for N parallel D3-branes is unaltered by this combination of terms. The non-vanishing of \zeroC^2 in this background (where \zero C is the background value of the Weyl tensor) leads to effective O(1/alpha') interactions, such as C^2 and Lambda^8 (where Lambda is the dilatino). These contain D-instanton contributions in addition to tree and one-loop terms. The near horizon limit of the N D3-brane system describes a multi-AdS_5xS^5 geometry that is dual to \calN=4 SU(N) Yang-Mills theory spontaneously broken to S(U(M_1)x...xU(M_r)). Here, the N D3-branes are grouped into r coincident bunches with M_r in each group, with M_r/N = m_r fixed as N goes to infinity. The boundary correlation function of eight Lambda's is constructed explicitly. The second part of the paper considers effects of a constrained instanton in this large-N Yang-Mills theory by an extension of the analysis of Dorey, Hollowood and Khoze of the one-instanton measure at finite N. This makes precise the correspondence with the supergravity D-instanton measure at leading order in the 1/N expansion. However, the duality between instanton-induced correlation functions in Yang-Mills theory and the dual supergravity is somewhat obscured by complications relating to the structure of constrained instantons.Comment: 30 pages, JHEP style. Typos corrected and minor clarifications adde

Explicit Formulas for Neumann Coefficients in the Plane-Wave Geometry

We obtain explicit formulas for the Neumann coefficients and associated quantities that appear in the three-string vertex for type IIB string theory in a plane-wave background, for any value of the mass parameter mu. The derivation involves constructing the inverse of a certain infinite-dimensional matrix, in terms of which the Neumann coefficients previously had been written only implicitly. We derive asymptotic expansions for large mu and find unexpectedly simple results, which are valid to all orders in 1/mu. Using BMN duality, these give predictions for certain gauge theory quantities to all orders in the modified 't Hooft coupling lambda'. A specific example is presented.Comment: 28 pages, 2 figures, v2: reference added, new comments and appendix, typos fixed in eqs. (86) and (89

Global symmetries and 't Hooft anomalies in brane tilings

We investigate the relation between gauge theories and brane configurations described by brane tilings. We identify U(1)_B (baryonic), U(1)_M (mesonic), and U(1)_R global symmetries in gauge theories with gauge symmetries in the brane configurations. We also show that U(1)_MU(1)_B^2 and U(1)_RU(1)_B^2 't Hooft anomalies are reproduced as gauge transformations of the classical brane action.Comment: 41 pages, 6 figure

On light-cone SFT contact terms in a plane wave

Testing the BMN correspondence at non-zero string coupling g_s requires a one-loop string field theory calculation. At order g_s^2, matrix elements of the light-cone string field theory Hamiltonian between single-string states receive two contributions: the iterated cubic interaction, and a contact term {Q, Q} whose presence is dictated by supersymmetry. In this paper we calculate the leading large mu p^+ alpha' contribution from both terms for the set of intermediate states with two string excitations. We find precise agreement with the basis-independent order g_2^2 results from gauge theory.Comment: 15 pages, 1 figur

Tadpole Cancellation in Unoriented Liouville Theory

The tadpole cancellation in the unoriented Liouville theory is discussed. Using two different methods -- the free field method and the boundary-crosscap state method, we derive one-loop divergences. Both methods require two D1-branes with the symplectic gauge group to cancel the orientifold tadpole divergence. However, the finite part left is different in each method and this difference is studied. We also discuss the validity of the free field method and the possible applications of our result.Comment: 12 pages; v2: sign error in the crosscap state is corrected, some related argumets are modified and clarified; v3: minor corrections; v4:reference adde