Efficient and Reusable PdCl2(MeCN)2/CuCl2/PEG‐400 System for Cyclization of Alkenyl β‐Keto Esters and Amides.

Li, Jin‐Heng; Zhu, Qi; Liang, Yun; Yang, Dan

doi:10.1002/chin.200545043

Cited by 2 publications

(2 citation statements)

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“…Recently, PEGs have been used for a variety of organic reactions such as the Suzuki coupling, 1-6 the Michael addition, 7 hydrogenation, [8][9][10][11] and so on. [12][13][14][15][16][17][18][19] Perrier et al 20 reported the first use of PEG as a polymerization solvent. They presume that the polarity and metal coordination ability of PEG would promote copper-catalyzed living radical polymerization of methyl methacrylate (MMA) and styrene.…”

Section: Introductionmentioning

confidence: 99%

Poly(ethylene glycol)-induced acceleration of free radical polymerization of methyl methacrylate: effects of highly viscous solvent and kinetic study

Matsuoka

Kikuno

Takagi

et al. 2010

Polym J

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Poly(ethylene glycol) with a molecular weight of 400 (PEG400) as an environmentally benign and highly viscous polymeric solvent was found to effectively accelerate the free radical polymerization (FRP) of methyl methacrylate and to afford a highmolecular-weight polymer. When the polymerization in PEG400 was performed at a monomer concentration of 3.0 mol l À1 and an initiator (2,2¢-azobis(isobutyronitrile)) concentration of 0.3Â10 À2 mol l À1 , the monomer conversion was completed for 6 h to afford a polymer with a number-average molecular weight (M n ) of 838 000. After polymerization, the PEG400 solvent was readily recovered and reused. The solvent effects of highly viscous PEG400 were kinetically analyzed. The polymerization rate (R p ) was proportional to the monomer concentration and the square root of both the initiator concentration and the viscosity of the polymerization media (g). For the FRP in the mixed solvents of PEG400 and toluene, both R p and M n values increased linearly with the square root of the g value. The kinetic study has shown that the highly viscous PEG400 solvent largely suppresses diffusion-controlled bimolecular termination.

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Section: Introductionmentioning

confidence: 99%

Poly(ethylene glycol)-induced acceleration of free radical polymerization of methyl methacrylate: effects of highly viscous solvent and kinetic study

Matsuoka

Kikuno

Takagi

et al. 2010

Polym J

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“…Recently, we (Chandrasekhar et al, 2002;Chandrasekhar et al, 2003;Chandrasekhar et al, 2014) and others (Jiang and Ragauskas, 2006;Huaxing et al, 2005;Li et al, 2005;Zhang et al, 2004) have demonstrated a new solvent medium, poly(ethylene glycol) (PEG) as an eco-friendly system for various functional group transformations. The importance of PEG as a biologically compatible polymer for drug delivery is well demonstrated and well approved by FDA for internal consumption (Harris, 1992;Herold et al, 1989;Veronese et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Total Synthesis of a Natural Product in Poly(ethylene Glycol):

Reddy¹

2015

Proceedings of the Indian National Science Academy

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A natural product, (±)-centrolobine was synthesized using only one non-conventional solvent [poly(ethylene glycol)-400] as a reaction medium for all the reactions involved such as allylation of aldehyde, olefin metathesis, Wittig olefination followed by intramolecular oxa-Michael reaction and hydrogenation. IntroductionThe use of volatile solvents in a chemical transformation occupies the maximum volume and recovery and/or minimizing this is an ever demanding process. Recently, we (Chandrasekhar et al., 2002;Chandrasekhar et al., 2003;Chandrasekhar et al., 2014) and others (Jiang and Ragauskas, 2006;Huaxing et al., 2005;Li et al., 2005;Zhang et al., 2004) have demonstrated a new solvent medium, poly(ethylene glycol) (PEG) as an eco-friendly system for various functional group transformations. The importance of PEG as a biologically compatible polymer for drug delivery is well demonstrated and well approved by FDA for internal consumption (Harris, 1992;Herold et al., 1989;Veronese et al., 2002). Thus, we believe the synthesis of any bioactive molecule in this solvent medium will certainly attract attention by both academic and pharma research groups. The efforts culminated in achieving the total synthesis of (±)-centrolobine in five steps including two one-pot reactions using poly(ethylene glycol) as a reaction medium in all the steps. Centrolobine (1, Fig. 1) is a tetrahydropyranic compound isolated from the heart wood of Centrolobium robustum (porcupine tree) and the stem of Brosimum potabile (Craveiro et al., 1970;de Albuquerque et al., 1964;Galeffi et al., 1965). The synthesis of 1 has attracted attention due to its activity against Leishmania amazonensis promastigotes; a parasite associated with et al., 1998;Boulard et al., 2004;Colobert et al., 2002;Carreno et al., 2003;Chan and Loh 2005;Chandrasekhar et al., 2005;Evans et al., 2003;Latif et al., 2015;Marumoto et al., 2002). Results and Discussions(±)-Centrolobine should be obtainable from lactol 2 and phosphonate 3 via Wittig olefination followed by intramolecular oxa-Michael reaction as key steps. The lactol 2 was further synthesized from commercially available aldehyde 4 using allylation, olefin metathesis followed by hydrogenation reactions (Scheme 1). The retrosynthetic strategy is designed in such a way that all reactions could be performed in PEG.The synthesis began with the preparation of homoallylic alcohol 5 which was achieved by metal mediated allylation of aldehyde in the presence of Lewis acid catalyst (Scheme 2). We have subjected 4-methoxy benzaldehyde 4 with allyl bromide using zinc powder in poly(ethylene glycol)-400 in the presence of CeCl 3 .7H 2 O as a Lewis acid catalyst. To the best of our knowledge this is the first example for allylation of aldehyde in PEG and could give the required product 5 in 89% yield. Encouraged by this result the recovery and reusability of the reagent system (PEG/Zn-CeCl 3 .7H 2 O) was also tried, but to our disappointment the yield of the product is decreasing for each run [The reaction medium, solvent an...

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Efficient and Reusable PdCl₂(MeCN)₂/CuCl₂/PEG‐400 System for Cyclization of Alkenyl β‐Keto Esters and Amides.

Cited by 2 publications

References 1 publication

Poly(ethylene glycol)-induced acceleration of free radical polymerization of methyl methacrylate: effects of highly viscous solvent and kinetic study

Poly(ethylene glycol)-induced acceleration of free radical polymerization of methyl methacrylate: effects of highly viscous solvent and kinetic study

Total Synthesis of a Natural Product in Poly(ethylene Glycol):

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