Synthesis of Benzyl 4-Hydroxy-5-iodo-2,3-dimethoxy-6-methylbenzoate: The Aromatic Unit of Calicheamicin g1

Orsellinic acid (6) was benzylated, and the benzyl 4-benzyloxy-2-hydroxy-6-methylbenzoate (7) was then elaborated into the title compound (2), which is the aromatic constituent of calicheamicin gamma1I

An unexpected photoadduct of N-carbomethoxymethylpyrrolidine with a chiral butenolide and benzophenone: X-ray structure and synthetic utility

The regio- and stereoselective photoinduced addition of N-carbomethoxymethylpyrrolidine to 5(S)-tert-butyldimethylsiloxymethyl-furan-2(5H)-one in the presence of benzophenone yields 3(R)-[N-(diphenylhydroxymethyl)carbo methoxymethylpyrrolidin-2′-yl]-4(S)-tert-butyldimethylsiloxymethyl)-butan-4-olides (epimeric at C-2′), and we report the X-ray structure of the major adduct together with its conversion into the 1-azabicyclo[4.3.0]-nonane ring system

Synthesis of new phytogrowth-inhibitory substituted Aryl-p-Benzoquinones

Reaction of [(2-alkyloxy)methyl]-1,4-dimethoxybenzene 10 (alkyl=butyl, hexyl, decyl, tridecyl, tetradecyl, hexadecyl, and octadecyl) with ceric ammonium nitrate in order to produce p-benzoquinones (=cyclohexa-2,5-diene-1,4-diones) afforded 5-[(alkyloxy)methyl]-2-(4-formyl-2,5-dimethoxyphenyl)benzo-1,4-quinones 12a-12g in yields that varied from 46 to 97%, accompanied by 2-[(alkyloxy)methyl]benzo-1,4-quinones 11a-11g in only small quantities (< or =5%). These quinones resemble the natural phytotoxic compound sorgoleone, found in Sorghum bicolor. This reaction exemplifies a general procedure for the synthesis of novel aryl-substituted p-benzoquinones. The selective effects of compounds 12a-12g, at the concentration of 5.5 ppm, on the growth of Cucumis sativus, Sorghum bicolor, Euphorbia heterophylla, and Ipomoea grandifolia were evaluated. All compounds caused some inhibition upon the aerial parts and root growth of the tested plants. The most active compound, 2-(4-formyl-2,5-dimethoxyphenyl)-5-[(tridecyloxy)methyl]-benzo-1,4-quinone (12d), caused between 3 and 18%, and 12 and 29% inhibition on the roots and aerial parts development of Cucumis sativus and Sorghum bicolor, respectively, and between 77 and 85%, and 34 and 52% inhibition on the roots and aerial parts growth of Euphorbia heterophylla and Ipomoea grandifolia, respectively

A novel alkaloid isolated from Crotalaria paulina and identified by NMR and DFT calculations

Pyrrolizidine alkaloids (PAs) are secondary metabolites found in Crotalaria genus and are known to have several biological activities. A novel macrocycle bislactone alkaloid, coined ethylcrotaline, was isolated and purified from the aerial parts of Crotalaria paulina. The novel macrocycle was identified with the aid of high resolution mass spectrometry and advanced nuclear magnetic resonance techniques. The relative stereochemistry of the alkaloid was defined by comparing the calculated quantum mechanical hydrogen and carbon chemical shifts of eight candidate structures with the experimental NMR data. The best fit between the eight candidate structures and the experimental NMR chemical shifts was defined by the DP4 statistical analyses and the Mean Absolute Error (MAE) calculations

Phosphorus transformation in poultry litter and litter-treated Oxisol of Brazil assessed by 31P-NMR and wet chemical fractionation

Large quantities of poultry litter are being produced in Brazil, which contain appreciable amounts of phosphorus (P) that could be of environmental concern. To assess the immediate environmental threat, five poultry litters composed of diverse bedding material were incubated for 43 days under greenhouse conditions. The litters consisted of: coffee bean husk (CH); wood chips (WC); rice husk (RH); ground corn cobs (CC) and ground napier grass (NG) (Pennisetum purpureum Schum.), in which the change in forms of soluble P was evaluated using 31P NMR spectroscopy. On average, 80.2 and 19.8 % of the total P in the extract, respectively, accounted for the inorganic and organic forms before incubation and 48 % of the organic P was mineralized to inorganic P in 43 days of incubation. Wide variation in the organic P mineralization rate (from 82 % -WC to 4 % - NG) was observed among litters. Inorganic orthophosphate (99.9 %) and pyrophosphate (0.1 %) were the only inorganic P forms, whereas the organic P forms orthophosphate monoesters (76.3 %) and diester (23.7 %) were detected. Diester P compounds were mineralized almost completely in all litters, except in the CH litter, within the incubation period. Pyrophosphates contributed with less than 0.5% and remained unaltered during the incubation period. Wood-chip litter had a higher organic P (40 %) content and a higher diester: monoester ratio; it was therefore mineralized rapidly, within the first 15 days, achieving steady state by the 29th day. Distinct mineralization patterns were observed in the litter when incubated with a clayey Oxisol. The substantial decrease observed in the organic P fraction (Po) of the litter types followed the order: CH (45 %) > CC (25 %) > RH (13 %) ≈ NG (12 %) > WC (5 %), whereas the Pi fraction increased. Incubation of RH litter in soil slowed down the mineralization of organic P.A avicultura intensiva tem se expandido bastante nos últimos anos no Brasil e, com isso, gerado grandes quantidades de cama de aviário. Esses materiais contêm quantidades substanciais de fósforo (P) - nutriente altamente limitante ao crescimento de plantas nos solos mais intemperizados, mas que pode causar impactos ambientais negativos se inadequadamente manejado. A fim de melhor subsidiar o uso mais sustentável desses materiais orgânicos, o presente trabalho teve como objetivo avaliar as formas e as transformações de P de camas de aviário obtidas com cinco diferentes materiais de forração do piso: casca de café, maravalha, casca de arroz, sabugo de milho triturado e capim-napier triturado. As camas de aviário foram incubadas por 43 dias, e as mudanças nas frações de P foram avaliadas por meio de espectroscopia de 31P RMN. Na média das cinco camas de aviário, 19,8 % do P total nos extratos encontrava-se na forma orgânica e 48 % do P dos compostos orgânicos foi mineralizado durante os 43 dias de incubação. Foi observada grande variação na mineralização desse nutriente entre as camas de aviário, de 4 % na cama de capim-napier até 82 % na cama de maravalha. Com exceção da cama de casca de café, os fostatos diéster foram quase totalmente mineralizados em todas as demais camas de aviário durante o período de incubação. O ortofofato inorgânico (99,9 %) e o pirofosfato (0,1 %) foram as únicas formas de P inorgânico detectadas, enquanto o P orgânico era composto por monoéster fosfatos (76,3 %) e diéster fosfatos (23,7 %). A contribuição do pirofosfato, menor que 0,5 %, permaneceu inalterada durante o período de incubação. A cama de maravalha apresentou a maior proporção de P na forma orgânica (40 %) e maior relação P diéster:P monoéster, resultando em rápida mineralização nos primeiros 15 dias de incubação, com estabilização a partir de 29 dias. Quando as camas de aviário foram incubadas com solo (Latossolo Vermelho-Amarelo), foram observados, na mineralização, distintos comportamentos entre elas. O decréscimo da fração de P em compostos orgânicos (Po) aplicados ao solo seguiu a ordem: casca de café (45 %) > sabugo de milho (25 %) > casca de arroz (13 %) ≈ capim-napier (12 %) > maravalha (5 %). Ao longo do período de incubação, foram observados incrementos no P inorgânico (Pi). A incubação da cama de casca de arroz com o solo reduziu a taxa de mineralização do seu Po. Portanto, a aplicação de cama de aviário em solos argilosos mais intemperizados pode ser uma alternativa segura de disposição e ciclagem das camas de aviário. No entanto, aplicações repetidas de doses elevadas de camas de aviário devem ser monitoradas para avaliar o risco de eutroficação de corpos de água devido ao P

Experimental and theoretical studies on the characterization of monocrotaline by infrared and Raman spectroscopies

The use of plants in folk medicine has a long and ancient history in the treatment of various diseases. Currently, a large proportion of commercial drugs are based on natural products or are synthetic compounds inspired on such natural substances. Therefore, in this communication to aid that research, structural and spectroscopic analysis of the natural pyrrolizidine alkaloid called monocrotaline was carried out. Pyrrolizidine alkaloids that are commonly found in the Boraginaceae and Asteraceae families are among the great diversity of secondary metabolites which are produced by plants to act as a defense mechanism against herbivores and microbes. In the present study, the natural product, monocrotaline, an alkaloid isolated from the leaves of Crotalaria paulina, with potential application in medicine, was characterized by infrared (IR) and Raman spectroscopy with the support of Density Functional Theory (DFT) calculations. IR and Raman spectra of monocrotaline were recorded at room temperature ranging from 4000 to 400 cm 1 . DFT calculations with the hybrid functional B3LYP and the basis set 6-31 þ G(d,p) were performed with the purpose of obtaining information on the structural and vibrational properties of this structure. A perfect fit between the experimentally measured frequencies of the IR and Raman spectra and the calculated values were observed, and we have performed the complete identification of monocrotaline by these techniques