Miguel J. Dabdoub’s research while affiliated with University of São Paulo and other places
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A simple synthesis of 3-iodothiophenes was demonstrated using a wide range of (Z)-thioenynes. The key step in the iodocyclofunctionalization was the selective reduction of the triple bond in (Z)-thioenynes by the addition of iodine as an electrophilic agent. The 3-iodothiophenes were obtained in good to excellent yields of 61–92%. The 3-iodothiophenes were used as substrates in Sonogashira cross-coupling reactions to obtain thiophene acetylenes.
An efficient and novel total synthesis of the two bioactive retinoids temarotene and arotinoid acid (TTNPB) is described. The key steps in this process include the regio and stereoselective hydrotelluration of thioacetylene 9 and Te/Li transmetalation of mixed (Z)-1,2-bis(organylchalcogene)-1-alkene (Z)-3. The subsequent reaction involving the β-phenylthio vinyl lithiated intermediate 10 with dimethyl sulfate gave the (E)-vinyl sulfide 11. The Ni+2 cross-coupling of 11 with the corresponding phenylzinc bromide and p-oxazoline phenylzinc bromide 12 afforded the respective temarotene 2 and retinoid-oxazoline substituted 13. Finally, compound 13 was deprotected with HCl to furnish arotinoid acid (TTNPB) 1.
Four- and eight-carbon homologation of benzaldehydes is described. The hydrotelluration of (Z)-1-methoxy-but-1-en-3-ynes 1 afforded (1Z,3Z)-1-butyltelluro-4-methoxy-1,3-butadiene 2, this compound 2 underwent a Te/Li exchange reaction, and the butadienyllithium 3 obtained reacted with benzaldehyde to form the corresponding allylic alcohol 4 with total retention of configuration. The allylic alcohol 4a formed underwent acidic hydrolysis, resulting in 5-phenyl-(2E,4E)-dienal 5 (four-carbon homologation of benzaldehyde). Product 5 reacted with the butadienyllithium 3, affording the alcohol 9-phenyl-(1Z,3Z,6E,8E)-1-methoxy-5-hydroxy-nonatetraene 6, which was hydrolyzed or spontaneously transformed into 9-phenyl-(2E,4E,6E,8E)-tetraenal 7, completing the eight-carbon homologation of benzaldehyde. Reaction of 9-phenyl-nona-(2E,4E,6E,8E)-tetraenal 7 with methyllithium in tetrahydrofuran afforded (3E,5E,7E,9E)-10-phenyl-deca-3,5,7,9-tetraen-2-ol 8. The product of the reaction described was employed in the synthesis of (3E,5E,7E,9E)-10-phenyl-deca-3,5,7,9-tetraen-2-one 9, which is known as navenone B, an alarm pheromone of the mollusk Navanax inermis.
A novel one-pot synthesis of 1,1-dihalo-1-alkenes and 1,1-bis(butyltelluro)-1-alkenes was developed from hydrozirconation of alkynylzinc bromide with Cp2Zr(H)Cl and subsequent capture of the Zn/Zr 1,1-heterodimetallo-1-alkene intermediates with halogen and tellurium electrophiles. These protocols, which include multiple reactions in a one-pot procedure, allow the preparation of the potentially useful haloketene acetals and telluroketene acetals from terminal alkynes, under mild conditions and in a good yield.
Sonogashira cross-coupling reactions involving (E)-iodo vinyl stannanes and terminal acetylenes were carried out in the presence of Pd(PPh3)4, CuI and several amines, affording (Z)-tributylstannyl enynes in moderate to good yields (62–91%). Utilizing the catalytic system containing Pd(PPh3)4 (5%), CuI (10%), and TBAOH (40% in aqueous media) as activator, better yields (72–91%) and lower reaction times were achieved.
Hydroalumination of phenylthioacetylenes with the Zweifel's reagent as reducing agent followed by the addition of C4H9TeBr afforded (Z)-telluro(thio)ketene acetals (Z >80-93%). The (E)-isomers were obtained with 100% stereoselectivity by reduction of thioacetylenes with DIBAL-H, followed by the addition of n-BuLi and subsequent treatment with C4H9TeBr. Reaction of the (E)-telluro(thio)ketene acetals with n-BuLi followed by the addition of valeraldehyde afforded the (Z)-phenylthio allylic alcohol as the main product and traces of the (E)-isomer, while the mixture of (Z)- and (E)-telluro(thio)ketene acetals under similar reaction conditions gave the (E)-phenylthio allylic alcohol exclusively.
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Citations (46)
... [52][53][54][55][56][57] The development of new methodologies for the synthesis of substituted telluro-, seleno-and thiophenes has been explored in the literature. Generally, these compounds are prepared by the cyclization of alkynes, dienes and diynes in the presence of inorganic chalcogen species [58][59][60][61] or via the intramolecular cyclization of organochalcogen compounds [62][63][64][65][66][67][68][69] and rearrangement reactions. [70] Among these procedures, Zeni and coworkers [71] described the cyclization of (Z)-chalcogenoenynes mediated by copper(II) salts (2.0 equiv) to afford 3-halochalcogenophenes (Scheme 1b). ...
... Recently and in a still timid manner, some studies using the design of experiments have been applied to fuel and biofuels, such as the prediction of the physical properties of biofuels [9], the evaluation of the correlation between the ratio of light biofuel and refined palm oil blends on their density and kinematic viscosity properties [10], and the minimisation of the kinematic viscosity and maximisation of the biodiesel yield during a transesterification reaction [11]. Furthermore, kinematic viscosity has been used in several studies regarding the quality of biodiesel [12][13][14][15]. ...
... The presence of saturated chains presents greater oxidative stability than that of unsaturated chains (DABDOUB et al., 2009), therefore, since most of the fatty acids in the biodiesel samples obtained in this study were unsaturated, consequently oxidative stability tends to be comparatively less. ...
... The addition of biodiesel in the blends and the type of biodiesel did not change the forward speed. These results are similar to those of Soranso et al. (2008), who worked with soybean soybean oil in agricultural tractors. ...
... Baroni et al. demonstrated the synthesis of 3-iodothiophenes from (Z)-thioenynes via iodocyclofunctionalization reaction in good to excellent yields. The key step involves the selective reduction of the triple bond in (Z)-thioenynes by the addition of iodine (Scheme 21) [31]. From similar substrates, Kesharwani et al. presented the preparation of 3chloro, 3-bromo and 3-iodo thiophenes through the reaction with inorganic salts. ...
... In other studies, we explored the use of NbCl5 in esterification reactions. This time, we are using NbCl5/Al2O3 in the synthesis of the benzyl ester [24] and graphite-coated niobium on silica in the synthesis of phenyl esters [31]. We studied the sequential reaction process because nucleophilic reagents act differently in transesterification and esterification reactions in the synthesis of MS in this new and innovative reaction process (Fig. 1), where the reactivity of the high valence transition metal niobium with ASA was investigated. ...
... The Retro-Favorski reaction between 23a-c with KOH under reflux in toluene generated terminal acetylenes 26a-c with 65%-85% yield (Dabdoub, Dabdoub, Guerrero & Hurtado, 2012). Ethynyl-1,2,3-trimethoxybenzene 26d was synthesized by the Corey-Fuchs method (Scheme 1) (Corey & Fuchs, 1972;Gibtner, Hampel, Gisselbrecht & Hirsch, 2002). ...
... Temarotene was isolated in 58% yield and 90% E selectivity from the cross-coupling of 17 and allylbenzene, whereas the analogous reaction of 17 with methyl 4-allylbenzoate followed by alkaline hydrolysis gave arotinoid acid in 39% overall yield and 91:9 E:Z ratio. The present sequences are more concise than a previously reported eight-step synthesis (for arotinoid acid) 48 and four-step synthesis (for temarotene) 49 . ...
... 433,456 Among many synthetic strategies towards unsaturated organotellurium compounds, the hydrotelluration Scheme 212 Synthesis of di(selenophen-3-yl)diselenides 1143 and diselenoles 1144 from 1-bromobutadiynes 1139. of diynes is a highly efficient and stereoselective method for enynyl tellurides which are useful building blocks in modern chemistry. Since the first synthesis of tellurophene by the interaction of 1,3-butadiyne 1a and 1152 with Na 2 Te 1153 in methanol developed by Mack's in 1966, 457 the several papers describing hydrotelluration of diynes appeared [458][459][460][461][462][463][464][465][466][467][468] which was also covered by Detty 431 and Zeni. 446,469 In this chapter the recent development of functionalisation of diynes by tellurium compounds will be presented. ...
... 6a was easily prepared by modifying a previously reported procedure (Supplementary Notes 2, 3, and 4 and Supplementary Figs. 19 and 20)38,39 and copolymerized with methyl acrylate (MA, 500 equivalents (equiv.)) in the presence of organotellurium CTA 9 12 at different [6a]/[9] ratios of 3, 7, 15, 31, and 63 in the presence of azobisisobutyronitrile (AIBN) (0.2 equiv.) as a radical initiator at 60°C(Fig. ...
