Catalyzed Diels-Alder

Lewis acids catalyze Diels-Alder reactions. Do they enhance overlap between diene and dienophile orbitals and/ or do they reduce the HOMO/LUMO energy difference ... [Pg.275]

Development of base-catalyzed Diels-Alder reaction of 3-hydroxy-2-pyrone and its application to synthesis of bioactive compounds 99YGK84. [Pg.225]

The Chiral Lewis Acid-catalyzed Diels-Alder Reaction 7... [Pg.7]

The Chiral Lewis Acid-catalyzed Diels-Alder Reaction 9 Fig. 1.1 CAB catalyst 3 and methacrolein Me... [Pg.9]

Seeeach et al. also investigated the Ti-TADDOlate-catalyzed Diels-Alder reaction, see D. Seeeach, R. Dahinden,... [Pg.55]

In most TiCl2-TADDOLate-catalyzed Diels-Alder and 1,3-dipolar cycloaddition reactions oxazolidinone derivatives are applied as auxiliaries for the alkenoyl moiety in order to obtain the favorable bidentate coordination of the substrate to the catalyst... [Pg.226]

Although Lewis acid-catalyzed-Diels-Alder reacdons of enones are common, there are few repoiTS on the catalysis of Dieis-Alder reacdon of nltroalkenes The reacdon of nltroalkenes with alkenes in the presence of Lewis acids undergoes a different course of reacdon to give cyclic nltronates fsee Secdon 8 3 Knochei repotted an enhanced reacdvity and seiecdvity of the intramolecular Dieis-Alder reacdon using silica gei as Lewis acid in hexane fEq 8 19 ... [Pg.239]

Lewis-Acid-Catalyzed Diels-Alder Reaction... [Pg.99]

This chapter will mostly deal with the applications of the Lewis-acid-catalyzed Diels Alder reaction to organic synthesis and the influence of Lewis acids on reactivity, stereoselectivity and regioselectivity of the cycloadditions. [Pg.100]

Table 3.1 Facialselectivity" in the aluminium chloride catalyzed Diels-Alder reactions of 4-, 5-and 6-substituted 2-cyclohexenones 5 with dienes 1-3...

Similarly a marked increase of regioselectivity has been shown in the catalyzed Diels-Alder reactions of the chiral bicyclic lactame 24 (Scheme 3.9) with a variety of dienes [27] (isoprene, mircene, (E,E)-L4-dimethylbutadiene, 2,3-di-methylbutadiene, 2-siloxybutadiene). The catalyzed reactions were more regio-selective and totally enJo-antz-diastereoselective anti with respect to the bridgehead methyl group). The results of the cycloadditions with isoprene and mircene are reported in Scheme 3.9. The cycloadducts have then been used to provide interesting fused carbocycles [28] with high enantiomeric purity as shown in Scheme 3.10. [Pg.107]

Dihydropyrans [71] and 4-dihydropyranones [72] have been prepared by BF3 or Me2AlCl catalyzed Diels-Alder reactions of alkyl and aryl aldehydes with dienes 72 and 73 (Equations 3.20 and 3.21). Allylic bis-silanes are useful building blocks for synthesizing molecules of biological interest [73], 4-Pyra-nones have been obtained by cerium ammonium nitrate (CAN) oxidation of the cycloadducts. [Pg.122]

Lewis-acid-catalyzed Diels-Alder reaction of 3-phenylthio-2- quinolinones with silox-ydiene. Synthesis of the intermediate for dynemicin A core [97]... [Pg.131]

Highly selective Lewis-acid-catalyzed Diels-Alder reactions of acyclic (Z)-1,3-dienes [104]... [Pg.133]

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