Diels-Alder additions asymmetric

Catalytic asymmetric hetero-Diels-Alder addition of carbonyl compounds 99ACR605. 

Asymmetric hefera-Diels-Alder addition of 1 -methoxybuta-1,3-diene to (2R)-N-pyruv-oyl-and (2R)-N-(phenylglyoxyloyl)bornane-10,2-sultam [69]... 

The sunuhaneous double Diels-Alder addition of l,l-bis(3,5-dimethylfur-2-yl)ethane (8) with a biS dienophile such as diethyl ( , )-4-oxohepta-2,5-diene-1,7-dioate was proposed as new, asymmetric synthesis of long-chain polypropionate fragments and analogues <96TL4149>. 

The asymmetric Diels-Alder addition is a powerful tool of organic chemistry therefore, its variant using diaza dienophiles has also been studied. When chiral diene 562, derived from (A)-phenylethylamine, is allowed to react... 

A more versatile method to use organic polymers in enantioselective catalysis is to employ these as catalytic supports for chiral ligands. This approach has been primarily applied in reactions as asymmetric hydrogenation of prochiral alkenes, asymmetric reduction of ketone and 1,2-additions to carbonyl groups. Later work has included additional studies dealing with Lewis acid-catalyzed Diels-Alder reactions, asymmetric epoxidation, and asymmetric dihydroxylation reactions. Enantioselective catalysis using polymer-supported catalysts is covered rather recently in a review by Bergbreiter [257],... 

Ab initio calculations on aza-Diels-Alder reactions of electron-deficient imines with buta-l,3-diene show that these reactions are HOMO (diene)-LUMO(dienophile)-controlled and that electron-deficient imines should be more reactive than alkyl-or aryl-imines. The Diels-Alder reaction of r-butyl 2//-azirine-3-carboxylate (80) proceeds with high diastereoselectivity with electron-rich dienes (81) (Scheme 28). The hetero-Diels-Alder additions of imines with sterically demanding dienes yield perhydroquinolines bearing an angular methyl group. The asymmetric hetero-Diels-Alder reaction between alkenyloxazolines and isocyanates produces diastereometri-cally pure oxazolo[3,2-c]pyrimidines. °... 

In 2006, Tan and co-workers reported the first asymmetric guanidine catalyzed Diels-Alder addition of anthrone to maleimides (Scheme 75) [130], The authors observed very high yields and enantioselectivities using a derivative of Corey s C2-symmetric bicyclic gnanidine catalyst. The addition of anthrones to maleimide also worked well for snbstitnted anthrones. Interestingly, the anthors observed the oxidized prodnct when the anthrone was substituted at the meto-positions (Scheme 76). 

The facially perturbed enantiopure (.S, .S )-2-(p-tolylsulfinyl)norborncno-/7-bcnzoquin-ones (119), undergo asymmetric Diels-Alder additions with cyclopentadiene to yield the four possible adducts (120) and (121). The endo-syn cycloadducts (121) can be used in the synthesis of the cage compound garudane (122) (Scheme 44).234 The antiaromatic compound 1,4-biphenylenequinone (123) has been synthesized and trapped by Diels-Alder reaction with cyclopentadiene (Scheme 45).235 The 4 + 2-cycloadditions of 4-methylene-5-(bromomethylene)-4,5-dihydrothiazole with 2- and 3-bromonaphtha-quinones are highly regiospecific.236... 

Tridentate salen ligands (10) derived from 1 have given excellent results in the enantiocontrol of the hetero Diels-Alder addition reaction of dienes with aldehydes (eq 7) and in the asymmetric additions of TMS-azide to mc5o-epoxide and trimethylsilyl cyanide to benzaldehyde (up to 85% ee). Phosphino-oxazolines derived from 1 have been employed for the asymmetric control of palladium-catalyzed allylic substitution reactions products of 70-90% ee were obtained. Photolysis of crystalline adducts of enantiomerically pure 1 with prochiral alcohols results in asymmetric inductions of up to 79% in a rare example of a solid-state enantioselective reaction. ... 

Table 19 Asymmetric Diels-Alder Additions of Cyclopcntadiene to o,p-Unsaturated A/-Acyloxazolidinones ...

Table 21 Asymmetric Diels-Alder Additions of Cyclopentadiene to N-Bnoylbomane 10,2-Sultams (Scheme 89)...

Table 22 Asymmetric Diels-Alder Additions of Butadiene and Isoprene to N-Aciyloylbotnane 10 -Sultams...

Table 27 Sulfoxide Directed Asymmetric Diels-Alder Additions to (2)-3-Arylsulfinylacrylates (Scheme 99)...

Diels-Alder reactions are enhanced by the complexation of dienophiles or dienes by Lewis acids [100]. Lewis acids have, furthermore, been successfully employed in asymmetric Diels-Alder additions [101]. Although SnCLt is a useful Lewis acid in Diels-... 

Gras, J L, Poncet, A, Nouguier, R, Ligand assisted asymmetric synthesis. II. Diastereoselective Diels-Alder additions with Lewis acid attracting auxiliaries derived from pentitols. Tetrahedron Lett, 33, 3323-3326, 1992. 

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