Reactions of guaiazulene with methyl terephthalaldehydate and 2-hydroxy- and 4-hydroxybenzaldehydes in methanol in the presence of hexafluorophosphoric acid: comparative studies on molecular structures and spectroscopic, chemical and electrochemical properties of monocarbocations stabilized by 3-guaiazulenyl and phenyl groups

Reaction of guaiazulene (1) with methyl terephthalaldehydate (2) in methanol in the presence of hexafluorophosphoric acid at 25 °C for 2 h under aerobic conditions gives (3-guaiazulenyl)[4-(methoxycarbonyl)phenyl]methylium hexafluorophosphate (5) in 94% yield. Similarly, reactions of 1 with 2-hydroxybenzaldehyde (3) and 4-hydroxybenzaldehyde (4) under the same reaction conditions as 2 give (3-guaiazulenyl)(2-hydroxyphenyl)methylium hexafluorophosphate (6) and (3-guaiazulenyl)(4-hydroxyphenyl)methylium hexafluorophosphate (7) in 89 and 97% yields, respectively. Comparative studies on the molecular structures as well as the spectroscopic, chemical and electrochemical properties of the monocarbocation compounds 5-7 stabilized by 3-guaiazulenyl and 4-(methoxycarbonyl)phenyl (or 2-hydroxy- or 4-hydroxyphenyl) groups are reported.     

Synthesis of caulersin and its isomers by reaction of indole-2,3-dicarboxylic anhydrides with methyl indoleacetates

1-Benzenesulfonylindole-2,3-dicarboxylic anhydride was reacted with methyl 1-benzenesulfonylindole-2-acetate to give the corresponding 2-acylindole-3-carboxylic acid as the sole product in high yield, which could be converted to caulersin in four steps. In a similar manner, three isomers A, B, and C were synthesized by reaction of indole-2,3-dicarboxylic anhydrides with methyl indoleacetates.     

Reactions of azulene and guaiazulene with all-trans-retinal and trans-cinnamaldehyde: comparative studies on spectroscopic, chemical, and electrochemical properties of monocarbenium-ions stabilized by expanded π-electron systems with an azulenyl or 3-guaiazulenyl group

Reaction of azulene (1) with all-trans-retinal in diethyl ether in the presence of hexafluorophosphoric acid at −10 °C for 1 h in a dark room gives the corresponding monocarbenium-ion compound, (2E,4E,6E,8E)-1-azulenyl-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8-nonatetraen-1-ylium hexafluorophosphate (3), in 74% isolated yield. The spectroscopic, chemical, and electrochemical properties of 3 compared with those of the previously-documented (2E,4E,6E,8E)-1-(3-guaiazulenyl)-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8-nonatetraen-1-ylium hexafluorophosphate (4) are reported. Along with the above delocalized monocarbenium-ion compounds 3 and 4, stabilized by the expanded π-electron systems possessing an azulenyl (or 3-guaiazulenyl) group, an efficient preparation as well as the spectroscopic, chemical, and electrochemical properties of (2E)-1-azulenyl-3-phenyl-2-propen-1-ylium and (2E)-1-(3-guaiazulenyl)-3-phenyl-2-propen-1-ylium hexafluorophosphates (5 and 6) (90 and 96% isolated yields), having a similar partial structure [i.e., the (2E)-1-azulenyl-2-propen-1-ylium-ion or (2E)-1-(3-guaiazulenyl)-2-propen-1-ylium-ion part] to those of 3 and 4, is documented. Moreover, the crystal structure of 6, whose carbenium-ion framework is planar, is shown.     

VioE, a prodeoxyviolacein synthase involved in violacein biosynthesis, is responsible for intramolecular indole rearrangement

Indole-3-pyruvic acid is transformed to prodeoxyviolacein by the novel enzyme VioE, which is involved in the violacein biosynthetic pathway in Chromobacterium violaceum ATCC12472. VioE catalyzes the decarboxylation and indole-ring rearrangement of a nascent compound that is produced from indole-3-pyruvic acid and by the action of chromopyrrolic acid synthase (VioB or StaD), and ultimately the reaction yields prodeoxyviolacein.     

Effect of electromagnetic environment effect on coherent and incoherent Cooper pair tunneling in superconducting C-SET

Cooper pair tunneling in voltage-biased superconducting C-SET structure is discussed with emphasis on the electromagnetic environment effect based on the self-consistent microscopic theory of Coulomb blockade in C-SET. It is shown that coherent Cooper pair tunneling survives only in the low impedance limit where charge fluctuation is large, while incoherent Cooper pair tunneling survives in both low- and high-impedance limits.     

Formation and structural observation of cesium encapsulated single-walled carbon nanotubes

Cesium encapsulation inside single-walled carbon nanotubes (SWNTs) is for the first time realized by ion irradiation of SWNTs immersed in a magnetized alkali-metal plasma, the configuration of which is confirmed to comprise three varieties by field emission type transmission electron microscopy (FE-TEM) and scanning TEM (STEM) observation.     

Discovery and Total Synthesis of Streptoaminals: Antimicrobial [5,5]‐Spirohemiaminals from the Combined‐Culture of Streptomyces nigrescens and Tsukamurella pulmonis

A series of lipidic spirohemiaminals, designated streptoaminals, is reported. These were discovered by surveying the unique molecular signatures identified in the mass spectrometry data of the combined‐culture broth of Streptomyces nigrescens HEK616 and Tsukamurella pulmonis TP‐B0596. Mass spectrometry analysis showed that streptoaminals appeared as a cluster of ion peaks, which were separated by 14 mass unit intervals, implying the presence of alkyl chains of different lengths. The chemical structures of these compounds were elucidated by spectroscopic analysis and total synthesis. Streptoaminals with globular structures showed broad antimicrobial activities, whereas the planar structures of the 5‐alkyl‐1,2,3,4‐tetrahydroquinolines found in the same combined‐culture did not. This work shows the application of microbes as reservoirs for a range of chemical scaffolds.     

The C4-functionalized 9,10-seco-5,7,10(19)-cholestatriene derivatives: Concise synthesis and characterization of novel vitamin D analogues with a four-membered heterocyclic ether

Two novel stereoisomeric 9,10-seco-steroids (3a,b) bearing a spiro-oxetane at the C2 position of the A-ring with an unconventional C4-hydroxy group have been designed and synthesized by a convergent manner. The requisite A-ring enyne precursors (±)-9 were prepared in excellent yield from our reported aldehyde 4 according to a five-step procedure. The absolute configurations at the C4-hydroxy groups of the targeted compounds (3a,b) were determined by the circular dichroism (CD) exciton chirality method using the corresponding benzoates of the C4-allylic alcohol. Preliminary biological characterization using the bovine thymus VDR suggested that the incorporation of a spiro-oxetane at the C2 position, in combination with a hydroxy group at the C4 position, had negative effects on the VDR affinity.     

Dramatic enhancement of antagonistic activity on vitamin D receptor: a double functionalization of 1alpha-hydroxyvitamin D3 26,23-lactones

The synthesis of novel vitamin D receptor antagonists, 24-methyl-1alpha-hydroxyvitamin D(3) 26,23-lactones, is reported. We found that the biological activities of the vitamin D(3) lactones were affected by the structure of the lactone part. Furthermore, introduction of a 2alpha-methyl group into the 24-methylvitamin D(3) lactones dramatically enhanced their anti-vitamin D activity. [reaction: see text]     

Preparation,molecular structures,and characteristic properties of (E)-1-(2-furyl)- and (E)-1-(2-thienyl)-2-(3-guaiazulenyl)ethylenes and (E)-1-(3-furyl)- and (E)-1-(3-thienyl)-2-(3-guaiazulenyl)ethylenes

Wittig reactions of 2-furaldehyde (20) [and thiophene-2-carbaldehyde (21)] with (3-guaiazulenylmethyl)triphenylphosphonium bromide (19) in ethanol containing NaOEt at 25 °C for 24 h under argon give (E)-1-(2-furyl)-2-(3-guaiazulenyl)ethylene (22E) and (E)-1-(2-thienyl)-2-(3-guaiazulenyl)ethylene (23E) in 53 and 36% yields. Similarly, Wittig reactions of 3-furaldehyde (29) [and thiophene-3-carbaldehyde (30)] with 19 under the same reaction conditions as for 20 and 21 afford (E)-1-(3-furyl)-2-(3-guaiazulenyl)ethylene (31E) and (E)-1-(3-thienyl)-2-(3-guaiazulenyl)ethylene (32E) in 32 and 46% yields. Molecular structures and characteristic properties as well as preparation of the title E (i.e., one of the geometrical isomers) forms, with a view to comparative study, are reported. Moreover, reactions of those conjugated π-electron systems with TCNE (=tetracyanoethylene) in benzene [and in DMF (=N,N-dimethylformamide)] at 25 °C for 24 h under argon yield unique products, possessing interesting molecular structures, respectively, whose characteristic properties and crystal structures are documented, also.