An asymptotic property of gap series

Takahashi [15] gave a concrete upper bound estimate of the law of the iterated logarithm for ∑ f(n _k x). We extend this result and prove the best possibility of this bound. This revised version was published online in August 2006 with corrections to the Cover Date.     

Penning ionization electron spectroscopy and photo-electron spectroscopy of molecular solids. II. Ammonia and water

The Penning ionization electron spectra (PIES) and ultraviolet photoelectron spectra (UPS) of ammonia and water molecules condensed on a cold metal substrate have been measured using thermal He*(2³S, 2¹S) metastable atoms and He(I) (58.4 nm) photons. The shifts of the observed positions of the PIES peaks relative to those of the UPS peaks in the condensed phase are roughly equal to the corresponding shifts in the gas phase. The relative intensities of the 3a₁ and 1e orbital peaks are reversed in the PIES and UPS for both gaseous and condensed ammonia; the origin of this reversal is interpreted as the difference between the interactions with metastable atoms and photons. On the other hand, the relative intensities of the 3a₁ orbital peak in the PIES and UPS for condensed water decrease as compared to the gas-phase spectra. This implies participation of the 3a₁ orbital of water in the hydrogen bonding.     

Spurring radical reactions of organic halides with tin hydride and TTMSS using microreactors

Tributyltin hydride-mediated radical reactions of organic halides were successfully carried out in a continuous flow system using a microreactor. The reactions proceeded within a very short period of time, coupled with quickly decomposing radical initiators such as V-65 and V-70. The continuous flow reaction system was applied to gram scale synthesis of a key intermediate for furofuran lignans.     

Tin-free Giese reaction and the related radical carbonylation using alkyl iodides and cyanoborohydrides

Tin-free Giese reaction and the related radical carbonylation process proceeded efficiently in the presence of sodium cyanoborohydride and tetrabutylammonium cyanoborohydride. The reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine and carbon-chlorine bonds. The iodine atom transfer followed by hydride reduction of the resulting carbon-iodine bond is proposed as a possible mechanism.     

Two new sesquiterpenoids and two new prenylated phenylpropanoids from Illicium fargesii, and neuroprotective activity of macranthol

Two new seco-prezizaane-type sesquiterpenoids 1, 2 and two new prenylated phenylpropanoids 4, 5 were isolated along with 15 known compounds from Illicium fargesii. The structures of 1, 2 were elucidated as 10-O-(E)- and 10-O-(Z)-cinnamoyl-2-oxo-6-deoxyneoanisatin by analysis of spectroscopic data and by comparison of their NMR data with those of previously reported 2-oxo-6-deoxyneoanisatin (3), respectively, whereas the structures of 4, 5 were identified as 4-allyl-2-(3-methylbut-2-en-1-yl)phenol and 4-allyl-2-(2-methylbut-3-en-2-yl)phenol, respectively, on the basis of spectroscopic data. Among the isolated compounds, macranthol (7) was found to have neuroprotective activity at 5--10 microM in rat cortical neurons cultured in DMEM/N2 medium.     

N,N'-ditosylhydrazine: a convenient reagent for facile synthesis of diazoacetates

A novel entry to the synthesis of diazoacetates is disclosed. A variety of diazoacetates were synthesized from the corresponding bromoacetates by treatment with N,N'-ditosylhydrazine in moderate to high yields. Ease of operation with the stable crystalline reagent as well as a short reaction time offer a useful alternative to the conventional methods.     

Design and synthesis of thiazoline-thiazole hybrid macrocycles possessing strong binding affinity to Pb2+ and Cd2+

Thiazoline-thiazole hybrid macrocycles were synthesized via head-to-tail cyclooligomerization. The macrocycle consisting of eight heterocyclic subunits displays high binding affinity to the heavy metal toxins Pb(2+) and Cd(2+).     

Stereocontrolled total synthesis of (-)-kainic acid

[reaction: see text] A stereocontrolled total synthesis of (-)-kainic acid is described. A fully functionalized trisubstituted pyrrolidine ring was constructed by ring-closing metathesis of an acrylate derivative followed by an intramolecular Michael addition of the resultant alpha,beta-unsaturated lactone with high diastereoselectivity. Two alternative protocols for the construction of the alpha,beta-unsaturated lactone were also developed.