Strategies towards the Synthesis of 6‐N,N‐Diethylcarbamyloxy‐1,4‐dimethoxy‐ 7‐naphthylboronic Acid

After acetylation, condensation between Danishefsky's diene and benzoquinone afforded a stable methoxytriacetoxydihydronaphthalene intermediate, which was subsequently transformed by the Snieckus DOM protocol into the regiospecific 7‐naphthylboronic acid.     

Two new alkylanacardic acids, ozorcardic A and B, from Ozoroa pulcherrima

Two new alkylanacardic acids, ozorcardic A (1) and B (2), along with the known and related metabolite anacardic acid (3), were isolated from Ozoroa pulcherrima. The structures of the new compounds were elucidated by detailed spectroscopic and spectrometric analysis.     

Citropremide and Citropridone: A New Ceramide and a New Acridone Alkaloid from the Stem Bark of Citropsis gabunensis

The structure elucidation and complete ¹H‐ and ¹³C‐NMR assignments are reported for two new compounds: the ceramide citropremide ( 1 ), and the acridone alkaloid citropridone ( 2 ). Both of these secondary metabolites were isolated from the stem bark of Citropsis gabunensis. High‐resolution mass, IR and UV spectrometry, and NMR experiments including COSY, HMQC, and HMBC were used for the determination of the structures and NMR spectral assignments.     

Naphthalene Disaccharide Fragments as Building Blocks for Angucycline Synthesis

ABSTRACT

Methods for the construction of naphthalene oligodeoxy disaccharide fragments, common structural elements of the angucycline antibiotics, are investigated. The triphenylphosphonium bromide- or scandium triflate-catalyzed addition of rhodinal to 4-OH silyl-protected olivoses affords the required 3-O-α-oligodeoxy disaccharides selectively and in high yields.     

Coriolis intensity perturbations of the ν4 band of SF6

In the ν₄ band of ³²SF₆ the intensity of absorption by the R branch has been found to exceed that of the P branch by 38%. This is substantially larger than the 15% excess that one calculates from ordinary rotational statistics and the nonnegligible width of the band. We attribute this imbalance to Coriolis interactions between the rovibrational sublevels (a) of the ν₃ and ν₄ excited vibrational states, and (b) of the ground vibrational state and the l = 1 (F_1g) level of the ν₃ + ν₄ combination state. The intensities of the observed P- and R-branch lines have a superposed Herman-Wallis type F factor of the form F(m) = (1 + ξ₄m)², where m = ?J for the P branch, 0 for the Q branch, and +(J + 1) for the R branch, and J is the rotational sublevel in the ground state. We have determined ξ₄ by a new method from the relative intensities of the P, Q, and R branches. New evidence is reported that supports an earlier conclusion that the first derivatives of the dipole moment function, $\text{μ}{}_3\text{=}\text{?μ}\text{?q}{}_3$ and $\text{μ}{}_4\text{=}\text{?μ}\text{?q}{}_4$, have the same sign. The corresponding Coriolis effect is calculated for UF₆. It is predicted that Coriolis interactions induce weak absorption in the ν₆ bands of SF₆ and UF₆, which would otherwise be inactive according to selection rules for strong infrared absorption or Raman scattering. An order-of-magnitude estimate of the absorption intensity of the induced ν₆ band of SF₆ agrees with a recent observation of that infrared spectral region.     

Four New Neoclerodane Diterpenoids from Ajuga decumbens

Four new neoclerodane diterpenoids, 15‐epilupulin A ( 1 ), 6‐O‐deacetylajugamarin ( 2 ), and ajugadecumbenins A ( 3 ) and B ( 4 ), were isolated from the whole plants of Ajuga decumbens. Their structures were elucidated on the basis of spectroscopic data and chemical correlations.     

Identification of the SF6 transitions pumped by a CO2 laser

The quantum numbers (J values and octahedral symmetry types) of the SF₆ transitions from the ground state to v₃ = 1 that fall within ± 1.5 G Hz of the CO₂ P(14), P(18), and P(20) laser lines have been assigned. The SF₆ absorptions nearest these three laser frequencies are R(28) A⁰₂, P(33) A¹₂, and an F₂ component of P(59) or P(60), respectively.     

Villarinol, a new alkenoyloxyalkenol derivative from the endemic Philippine Rubiaceae species Villaria odorata

Villarinol (1), a new alkenoyloxy alkenol metabolite, has been isolated from the dichloromethane extract of Villaria odorata, an endemic Rubiaceae Philippine plant, along with the known compounds stigmasterol and 4-hydroxybenzaldehyde. The structure of 1 was elucidated on the basis of spectroscopic and spectrometric studies. The extracts of V. odorata exhibited moderate inhibition against Mycobacterium tuberculosis H37Rv, based on the colorimetric microplate alamar blue assay.