A general method for acylation of indoles at the 3-position with acyl chlorides in the presence of dialkylaluminum chloride

[reaction--see text] Indoles are selectively acylated at the 3-position in high yields on treatment with a wide variety of acyl chlorides in CH(2)Cl(2) in the presence of diethylaluminum chloride or dimethylaluminum chloride. The reaction proceeds under mild conditions and is applicable to indoles bearing various functional groups without NH protection.     

LIGHT-INDUCED SYNTHESIS OF ANTHOCYANIN IN CARROT CELLS IN SUSPENSION—IV. THE ACTION SPECTRUM

Abstract— Using carrot cell suspension in 2,4-dichlorophenoxyacetic acid (2,4-D)-depleted culture medium, fluence-response curves for the formation of anthocyanin were determined at various wavelengths from 250 to 800 nm. In the fluence-response curves at wavelengths between 260 and 330 nm, the response showed a sharp fluence-dependent increase after the fluence exceeded threshold level at the respective wavelength. Such a sharp increase in response was not observed by light at 450 nm or longer wavelengths, although the response obtained by higher fluence of such light was always higher than that in the dark control. Action spectra determined at the sharp increasing phase of the response showed the single peak at 280 nm which equals the absorption maximum of UV-B photoreceptor.
Although red (R)-light alone had a minor effect on anthocyanin accumulation, it modulated the action of UV-B light. That is, when carrot cells were irradiated with R-light either before or after UV-B irradiation, anthocyanin formation was greatly enhanced above the level enhanced by UV-B light alone. The most effective wavelength for this enhancement was 660 nm. The effect of R-light on the anthocyanin formation of the UV-B irradiated cells was reversed by immediately following it with far-red light, suggesting the involvement of phytochrome in the R-effect.     

Synthetic Utilization of α-Phosphonovinyl Anions

The α-phosphonovinyl anions, generated in situ from treatment of β-hetero-substituted vinyl-phosphonates 1a-c with LDA (or LTMP), were trapped with various electrophiles such as chlorotriorganosilanes, chlorotrimethylgermane, chlorotriorganotins, dimethyl disulfide, and halogen to afford the corresponding β-hetero-substituted α-functionalized vinylphosphonates 2–14 in good to excellent yields. The Friedel-Crafts reaction of α-(silyl) or α-(germyl)phosphonoketene dithioacetals 2, 9 or 4 with acid chlorides gave α-acylated phosphonoketene dithioacetals 15–19 in 53–91 % yields. The palladium-catalyzed cross-coupling reaction of β-ethoxy-α-(tributylstannyl)vinylphosphonate 13 with a variety of organic halides (R = acyl, allyl, aryl etc.) provided β-ethoxy-α-substituted vinylphosphonates 20–25 in good to moderate yields. The palladium-mediated cross-coupling reaction of α-(iodo)-vinyl-phosphonates 7, 14 with terminal acetylenes afforded α-alkynylated vinylphosphonates 26–29 in 69–83 % yields.     

Classification Performance of a Low Pressure Differential Mobility Analyzer for Nanometer-sized Particles

Size distribution measurements and classification tests by a low pressure differential mobility analyzer (LPDMA) for nanometer-sized silver particles and cesium iodide particles under low pressure conditions (123–300 Torr) were performed using a transmission electron microscope (TEM) and the tandem DMA technique. When the ratio of the sheath gas flow rate and the aerosol gas flow rate was set at 5 : 1, the targeted sizes calculated from the classification voltage applied to the LPDMA at 160 Torr are found to be in good correlation with the count mean Feret diameter obtained from the TEM observation of the particles collected after a classification ranging from 6 to 25 nm, although the targeted sizes set by the LPDMA were approximately 15% greater than the count mean Feret diameter measured by the TEM after classification. The geometric standard deviations of DMA-classified particles measured by TEM and those obtained from the tandem DMA method ranged from 1.08 to 1.17 and from 1.05 to 1.13, respectively. They were slightly greater than the ideal geometric standard deviations (1.05) of the particles classified with the LPDMA, which was calculated by neglecting the broadening effects due to Brownian diffusion. We experimentally demonstrated the validity of our LPDMA system for size measurements and classification of the nanometer-sized particles under low pressure conditions.     

Lewis Acid-Catalyzed Intramolecular [2 + 2] Cycloaddition of alpha-Ester-Substituted Conjugated Dienyl- and Trienylphosphonates. New Synthesis of Functionalized Cyclic Terpenoids

alpha-Ester-substituted 1,3-dienylphosphonates 7 and 8, prepared by the Knoevenagel condensation, underwent intramolecular [2 + 2] cycloaddition in the presence of Lewis acid to form bicyclo[4.2.0] (26-57% yield) and bicyclo[3.2.0]skeleton (14-38% yield), respectively. Similar treatment of homologous 1,3-dienylphosphonate 11 and 1,3,5-trienylphosphonate 12 resulted in the formation of ionone derivatives (30-94% yield). The intramolecular cycloaddition reaction was applicable to several conjugated dienes bearing an ester group.     

Lewis acid-promoted deoxygenative di[beta,beta-bis(ethylthio)]vinylation of aldehydes with trimethylsilylketene bis(ethylthio)acetal

Silylketene dithioacetal 1 reacted with aldehydes 2a-o, 14, or cinnamaldehyde (11) in the presence of Lewis acid to give deoxygenative divinylation products, 3-substituted 1,4-pentadienes 3a-o, 15, or 5-phenyl-1,3,6-heptatriene 13b, in good to moderate yields. Similar reaction with 2-aminobenzaldehyde (16) or salicylaldehyde (17) produced quinoline 19 or chroman 20 in 40-58% yield. Treatment of 1 with alpha-diketones 22a-c or alpha-ketoester 24 led to tetrasubstituted furans 23a-c or allylic alcohol 25, respectively, in rather low yields. The formation mechanisms of these products are discussed.     

Synthesis and Chiroptical Properties of Quinoxaline-Fused Polyaza[5]–[7]helicenes with Orange-Color CPL Emissions

We achieved a two-type synthesis of quinoxaline-fused polyaza[5]- and [7]helicenes through consecutive N−H/C−H coupling with a hypervalent iodine reagent as a key reaction. By fusing electron-deficient quinoxaline, these polyazahelicenes constitute an efficient donor-acceptor type of molecule with absorption edges that reach up to approximately 650 nm. Evaluating the chiroptical properties reveals that the polyazahelicene exhibits a rare orange circularly polarized glow with a luminescence dissymmetry factor (g_lum value) of 0.003.     

Synthesis of 1,2-naphthalenediol derivatives by Rh-catalyzed intermolecular OH insertion reaction of 1,2-diazonaphthoquinones with water and alcohols

Rh(II)-catalyzed OH insertion reaction of diazonaphthoquinones with water or alocohols proceeded to yield 1,2-naphthalenediol derivatives.     

Synthesis of α,α-diarylacetamides from benzyl aryl ketones using 2-azido-1,3-dimethylimidazolinium hexafluorophosphate

Benzyl aryl ketones reacted with 2-azido-1,3-dimethylimidazolinium hexafluorophosphate (ADMP, 1) to give migratory amidated compounds, which were transformed into the corresponding diarylacetamides by treating with LiAlH₄.     

The first synthesis of phosphonoacrolein. Application to Diels-Alder reaction as heterodiene

The first synthesis of phosphonoacrolein 3 was made in quantitative yield by acidic treatment of beta-ethoxy-alpha-(methoxymethyl)vinylphosphonate 2, derived from a beta-ethoxy-alpha-phosphonovinyl anion and MOMCl. The phosphonoacrolein 3 easily underwent a hetero-Diels-Alder reaction with electron-rich alkenes 4a-f or alkynes 9a-c under mild conditions, and phosphono-substituted pyrans 5a-d, 6e,f or pyranopyrans 11a-c were obtained in good to excellent yields. The reaction of 3 with cyclopentadiene and cyclohexadiene led to mixtures of [2 + 4] and [4 + 2] cycloadducts 7a, 8a and 7b, 8b in modest yields. The cycloaddition reaction between 3 and pyranopyran 13 or dibromocarbene and 13 resulted in [4 + 2] or [2 + 1] cycloadducts 14 or 15 in good yields.