Diels-Alder reaction of butadiene with

The carbo-Diels-Alder reaction of acrolein with butadiene (Scheme 8.1) has been the standard reaction studied by theoretical calculations in order to investigate the influence of Lewis acids on the reaction course and several papers deal with this reaction. As an extension of an ab-initio study of the carbo-Diels-Alder reaction of butadiene with acrolein [5], Houk et al. investigated the transition-state structures and the origins of selectivity of Lewis acid-catalyzed carbo-Diels-Alder reactions [6]. Four different transition-state structures were considered (Fig. 8.4). Acrolein can add either endo (N) or exo (X), in either s-cis (C) or s-trans (T), and the Lewis acid coordinates to the carbonyl in the molecular plane, either syn or anti to the alkene. 

In contrast with exo (top) facial selectivity in the additions to norbomene 80 [41], Diels-Alder reaction between isodicyclopentadiene 79 takes place from the bottom [40] (see Scheme 32). To solve this problem, Honk and Brown calculated the transition state of the parent Diels-Alder reaction of butadiene with ethylene [47], They pointed ont that of particular note for isodicyclopentadiene selectivity issue is the 14.9° out-of-plane bending of the hydrogens at C2 and C3 of butadiene. The bending is derived from Cl and C4 pyramidalization and rotation inwardly to achieve overlap of p-orbitals on these carbons with the ethylene termini. To keep the tr-bonding between C1-C2 and C3-C4, the p-orbitals at C2 and C3 rotate inwardly on the side of the diene nearest to ethylene. This is necessarily accompanied by C2 and C3 hydrogen movanent toward the attacking dienophile. They proposed that when norbomene is fused at C2 and C3, the tendency of endo bending of the norbomene framework will be manifested in the preference for bottom attack in Diels-Alder reactions (Schane 38). 

Inubushi s synthesis of racemic serratinine commences with a Diels-Alder reaction of butadiene with substituted quinone derivative 26 (available in four steps from 25,... 

These experimental secondary deuterium KIEs observed in Diels-Alder reactions have been compared with the respective theoretical KIEs for the stepwise mechanism involving a diradical intermediate (equation 88a) and for concerted synchronous and asynchronous mechanisms (equation 88b) for the Diels-Alder reaction of butadiene with ethylene207. 

Because a comprehensive discussion of the transition state of hydrogen-bond catalysis will be presented by Berkessel in Chapter 3, the hydrogen bond catalyzed hetero Diels-Alder reaction of butadiene with carbonyl compounds will be discussed briefly here. Huang and Rawal reported that the hetero Diels-Alder reaction of aminodiene with aldehyde exhibited significant solvent effects (Scheme 2.7) [15]. The reaction in CHCfi was accelerated 30 times in comparison with that in THF, while that in i-PrOH was accelerated 630 times. They proposed that the Diels-Alder reaction was promoted by the hydrogen-bond activation of aldehyde. This finding resulted in the development of TADDOL catalyst [3]. 

Dichlorodibutyl ether, 27 Diels-Alder reaction of butadiene with maleic anhydride, 93 Diene synthesis of cis-A -tetrahydro-phthalic anhydride, 93 Diethyl benzalmalonate, 84 Diethyl carbonate, 44 Diethyl fumarate, 46 Diethyl cis-HEXAiiYDROPiiTHALATE, 29 Diethyl malonate, 70 Diethyl o-nitrobenzoylmalonatc, 71 Diethyl sodium phthalimidomalonate, 7... 

Teplyakov, A. V., Kong, M. J. and Bent, S. F. Diels-Alder reactions of butadienes with the Si(100)-2 x 1 surface as a dienophile vibrational spectroscopy, thermal-desorption and nearedge X-ray-absorption fine-structure studies. Journal of Chemical Physics 108, 4599 1606 (1998). 

Fig. 3.11 Using molecular mechanics to get the (approximate) transition state for the Diels-Alder reaction of butadiene with ethene. This procedure gives a structure with the desirable Cs, rather than a lower, symmetry...

We will not develop all of the Woodward-Hoffmann rules, but we will show how the molecular orbitals can indicate whether a cycloaddition will take place. The simple Diels-Alder reaction of butadiene with ethylene serves as our first example. The molecular orbitals of butadiene and ethylene are represented in Figure 15-18. Butadiene, with four atomic p orbitals, has four molecular orbitals two bonding MOs (filled) and two antibonding MOs (vacant). Ethylene, with two atomic p orbitals, has two MOs a bonding MO (filled) and an antibonding MO (vacant). 

For the preparation of diethyl trans- A4-tetrahydrophthalate, the present synthesis is superior to the Diels-Alder reaction of butadiene with diethyl fumarate4 for the reasons given above In addition, a higher yield is obtained at a lower reaction temperature and shorter reaction time. 

Bimey, D. M. Houk, K. N. Transition structures of the Lewis acid-catalyzed Diels-Alder reaction of butadiene with acrolein. The origins of selectivity, 7. Am. Chem. Soc. 1990,112, 4127-4133. 

The benzo[a]anthraquinone skeleton 56 was also formed in an interesting rearrangement of a spirodienone 55 prepared by Diels-Alder reaction of butadiene with the spiro-quinone 54 [57]. 

Sakai, S. Theoretical analysis of concerted and stepwise mechanisms of the hetero-Diels-Alder reaction of butadiene with formaldehyde and thioformaldehyde. THEOCHEM 200Z, 630, 177-185. 

Houk KN, Lin YT, Brown FK. Evidence for the concerted mechanism of the Diels-Alder reaction of butadiene with ethylene. J Am Chem Soc 1986 108 554-556. 

Fig. 10.9. Asynchronous transition structures for Diels-Alder reactions of butadiene with maleic acid and 1,2,4-triazoline using B3LYP/6-31G calculations. Reproduced from Tetrahedron, 57, 5149 (2001) and J. Am. Chem. Soc., 120, 12303 (1998), by permission of Elsevier and the American Chemical Society, respectively.

Figure 13.19 Calculated (IGLO/IIMP2(fu)/6-31C ) chemical NMR shifts of the protons (marked with , O, A, , and X) in the Diels-Alder reaction of butadiene with ethylene. The proton labeled as X protrudes into the shielding range of the ring current in the transition state, and therefore exhibits...

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