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《Journal of carbohydrate chemistry》2013,32(5):431-443
Triacetylglucal (1) is converted with high α-selectivity (>9:1) to the corresponding 2,3-unsaturated allyl and benzyl glycosides 2 and 3 using ferric chloride as the catalyst. The 6-O-silyl-protected allylic alcohol 5 is transformed to the 3,4-unsaturated C2-branched ester 6 or the amide 7 by Claisen rearrangement. The highly deoxygenated iodo lactone 8, resulting from the amide 6 by iodolactonization, is a versatile starting material for chiral building blocks 9–12. The 3,4-unsaturated C2-branched ester 6 is reduced to the aldehyde 14 and converted to a carbon linked disaccharide analogue 16 via cycloaddition with Danishefky's diene. 相似文献
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Carla Vilela Armando J. D. Silvestre Alessandro Gandini 《Journal of polymer science. Part A, Polymer chemistry》2013,51(10):2260-2270
Novel trifunctional monomers based on renewable resources were prepared and subsequently polymerized via the Diels‐Alder (DA) polycondensation between furan and maleimide complementary moieties. Three basic approaches were considered for these nonlinear DA polycondensations, namely the use of (i) a bisfuran monomer in combination with a trismaleimide (A2 + B3 system) and (ii) a trisfuran monomer in conjunction with a bismaleimide (A3 + B2 system) leading to branched or crosslinked materials, and (iii) the use of monomers incorporating both furan and maleimide end groups (A2B or AB2 systems), which lead to hyperbranched structures. The application of the retro‐DA reaction to the ensuing polymers confirmed their thermoreversible character. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
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Loyd D. Bastin Sam Martinus James E. Maloney Landon L. Benyack Brendan Gainer 《Green Chemistry Letters and Reviews》2019,12(2):127-135
ABSTRACTThis paper describes the design and implementation of a minimally hazardous, environmentally friendly, and energy efficient sequential reaction sequence within a sophomore level Organic Chemistry lab course to efficiently synthesize N-phenylmaleimide precursors for a Diels–Alder reaction. Substituted N-phenylmaleimides are a class of very expensive precursors of considerable interest due to their biological properties and use as intermediates in synthesis. The synthesis described herein produces a substituted N-phenylmaleimide in two steps from maleic anhydride and a substituted aniline followed by its Diels–Alder reaction with 2,5-dimethylfuran. The experiment exposes students to the green chemistry principles of atom economy, use of safer chemicals, design for energy efficiency, waste reduction, and inherently safer chemistry for accident prevention and enables students to use 1H NMR spectroscopy to characterize the products. 相似文献
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The cycloadducts 2A‐5A obtained from the Diels‐Alder cycloadditions of 1,2,3,4‐tetrachloro‐4,5‐dimethoxycyclopentadiene ( 1 ) with p‐benzoquinone ( 2 ), 1,4‐naphthoquinone ( 3 ), 1,4‐anthraquinone ( 4 ), and 2,3‐dicyano‐1,4‐benzoquinone ( 5 ) were subjected to the reaction with triethylamine in dichloromethane at room temperature. Cycloadducts 2A and 5A enolized to give the corresponding hydroquinones 2B and 5B , which were oxidized with DDQ to afford naphthoquinone ester 2D and anthraquinone ester 5D , respectively. In the cases of cycloadducts 3A and 4A , the enolization occurred concurrently with oxidation and fragmentation to produce directly the polyacenoquinone esters 3D and 4D , respectively. Under the same reaction condition, the unsymmetrical cycloadduct 6A derived from naphthoquinone ester 2D and 1 yielded isomeric polyacenoquinone esters 6Da and 6Db in a ratio of about 8:1. 相似文献