| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1347326 | Tetrahedron: Asymmetry | 2009 | 11 Pages |
Compared to enantioselective Friedel–Crafts reactions of indoles, reactions of alkylidene malonates with monocyclic aromatic compounds generally proceed with low enantioselectivity. The Friedel–Crafts reactions of ethenetricarboxylates 1 and monocyclic heteroaromatic compounds, such as substituted pyrroles and furans were investigated. The reaction of 1 with 2,4-dimethylpyrrole in the presence of a chiral bisoxazoline–copper(II) complex (10 mol %) in tetrahydrofuran at room temperature gave alkylated products in up to 72% ee. The reaction of 1 with 2-substituted furans gave alkylated products in 46–62% ee. The absolute stereochemistry of the furan Friedel–Crafts product 7e was determined by transformation to the known 2,3-dimethylbutyric acid. The intramolecular reaction of benzene derivatives gave cyclized products up to 56% ee.
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1-tert-Butyl 2,2-diethyl 1-(5-butylfuran-2-yl)ethane-1,2,2-tricarboxylateC21H32O7Ee = 58%[α]D22=-59 (c 1.02, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]Absolute configuration: (R)
1-tert-Butyl 2,2-diethyl 1-(3,5-dimethyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC19H29NO6Ee = 72%[α]D30=-75 (c 1.06, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC17H25NO6Ee = 29%[α]D32=-20 (c 0.96, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(1-ethyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC19H29NO6Ee = 10%[α]D23=-15 (c 1.55, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(1-phenyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC23H29NO6Ee = 10%[α]D21=+10 (c 1.80, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(1-phenyl-1H-pyrrol-3-yl)ethane-1,2,2-tricarboxylateC23H29NO6Ee = 66%[α]D14=-76 (c 0.15, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(5-ethyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC19H29NO6Ee = 45%[α]D26=-40 (c 0.99, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(5-benzyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC24H31NO6Ee = 41%[α]D24=-37 (c 1.02, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(3-phenyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC23H29NO6Ee = 66%[α]D23=-99 (c 0.50, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(4-phenyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC23H29NO6Ee = 12%[α]D27=+11 (c 0.22, CHCl3)Source of chirality: (+)-2,2′-isopropylidenebis[(4R)-4-benzyl-2-oxazoline]
1-tert-Butyl 2,2-diethyl 1-[3-(4′-chlorophenyl)-1H-pyrrol-2-yl]ethane-1,2,2-tricarboxylateC23H28ClNO6Ee = 50%[α]D22=-77 (c 1.23, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-[4-(4′-chlorophenyl)-1H-pyrrol-2-yl]ethane-1,2,2-tricarboxylateC23H28ClNO6Ee = 28%[α]D26=-13 (c 0.20, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-dibenzyl 1-(3,5-dimethyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC21H32O4Ee = 38%[α]D26=-35 (c 1.00, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1,2,2-Triethyl 1-(3,5-dimethyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC17H25NO6Ee = 63%[α]D21=-96 (c 1.24, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-(4-Bromobenzyl) 2,2-diethyl 1-(3,5-dimethyl-1H-pyrrol-2-yl)ethane-1,2,2-tricarboxylateC22H26BrNO6Ee = 48%[α]D23=-38 (c 0.54, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
Diethyl 2-[1-(3,5-dimethyl-1H-pyrrol-2-yl)-2-oxo-2-(piperidin-1-yl)ethyl]malonateC20H30N2O5Ee = 71%[α]D27=-118 (c 1.08, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
Diethyl 2-[1-(3,5-dimethyl-1H-pyrrol-2-yl)-2-oxo-2-phenylethyl]malonateC21H25NO5Ee = 41%[α]D22=-83 (c 1.68, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
Diethyl 2-[(3,5-dimethyl-1H-pyrrol-2-yl)(phenyl)methyl]malonateC20H25NO4Ee = 47%[α]D19=-10 (c 0.56, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
1-tert-Butyl 2,2-diethyl 1-(furan-2-yl)ethane-1,2,2-tricarboxylateC17H24O7Ee = 9%[α]D28=-8 (c 0.31, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]
1-tert-Butyl 2,2-diethyl 1-(5-methylfuran-2-yl)ethane-1,2,2-tricarboxylateC18H26O7Ee = 46%[α]D24=-52 (c 0.95, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]
1-tert-Butyl 2,2-diethyl 1-(5-ethylfuran-2-yl)ethane-1,2,2-tricarboxylateC19H28O7Ee = 60%[α]D30=-63 (c 1.07, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]
1-tert-Butyl 2,2-diethyl 1-(5-propylfuran-2-yl)ethane-1,2,2-tricarboxylateC20H30O7Ee = 57%[α]D28=-62 (c 1.48, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]
1-tert-Butyl 2,2-diethyl 1-(4,5-dimethylfuran-2-yl)ethane-1,2,2-tricarboxylateC19H28O7Ee = 27%[α]D22=-29 (c 1.01, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
(S)-2-(Hydroxymethyl)-3-(5-butylfuran-2-yl)butane-1,4-diolC13H22O4Ee = 62%[α]D17=-5.8 (c 1.35, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]Absolute configuration: (S)
(R)-2-Butyl-5-(1,2-dimethypropyl)furanC13H22OEe = 62%[α]D16=-6.3 (c 0.66, CHCl3)Source of chirality: (−)-2,2′-methylenebis[(3aS,8aR)-3a,8a-dihydro-8H-indeno[1,2-d]oxazole]Absolute configuration: (R)
Diethyl 2-(1,2,3,4-tetrahydro-6,8-dimethoxy-2-oxonaphthalen-1-yl)malonateC19H24O7Ee = 48%[α]D31=+90 (c 0.75, CHCl3)Source of chirality: (+)-2,2′-isopropylidenebis[(4R)-4-benzyl-2-oxazoline]
Diethyl 2-(5,7-dimethoxy-3-oxochroman-4-yl)malonateC18H22O8Ee = 20%[α]D26=+38 (c 1.19, CHCl3)Source of chirality: (S,S)-(−)-2,2′-isopropylidenebis(4-tert-butyl-2-oxazoline)
Diethyl 2-(6,8-bis(benzyloxy)-1,2,3,4-tetrahydro-2-oxonaphthalen-1-yl)malonateC31H32O7Ee = 56%[α]D30=+109 (c 0.85, CHCl3)Source of chirality: (+)-2,2′-isopropylidenebis[(4R)-4-benzyl-2-oxazoline]
