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Convergent and stereodivergent synthesis of complex 1-aza-7-oxabicyclo[2.2.1]heptanes.

ABSTRACT: A convergent and stereodivergent pathway to highly substituted 1-aza-7-oxabicyclo[2.2.1]heptanes is described. It begins with a coupling reaction involving allylic alcohol, aldehyde, and LiHMDS to produce stereodefined primary homoallylic amines. Subsequent N-oxidation and condensation with formaldehyde or glyoxylate defines a convenient entry to densely functionalized homoallylic nitrones whose intramolecular annulation can be controlled to deliver one of two distinct heterocyclic skeletons, each with ?20:1 stereoselection. Control of the stereochemistry in these reactions results from both control of the nitrone geometry and selective partitioning of the reaction pathway between direct [3 + 2] cycloaddition and tandem [3,3] rearrangement/[3 + 2] cycloaddition.

SUBMITTER: Yang D

PROVIDER: S-EPMC3116711 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Convergent and stereodivergent synthesis of complex 1-aza-7-oxabicyclo[2.2.1]heptanes.

Yang Dexi D Micalizio Glenn C GC

Journal of the American Chemical Society 20110523 24

A convergent and stereodivergent pathway to highly substituted 1-aza-7-oxabicyclo[2.2.1]heptanes is described. It begins with a coupling reaction involving allylic alcohol, aldehyde, and LiHMDS to produce stereodefined primary homoallylic amines. Subsequent N-oxidation and condensation with formaldehyde or glyoxylate defines a convenient entry to densely functionalized homoallylic nitrones whose intramolecular annulation can be controlled to deliver one of two distinct heterocyclic skeletons, ea ...[more]

PMID: 21604673

Similar Datasets

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols.

Project description:The acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicylic alkene using alcohol nucleophiles were investigated. Although this acid-catalyzed ring-opening reaction did not cleave the cyclopropane unit as planned, this represent the first examples of ring-openings of cyclopropanated 3-aza-2-oxabicyclo[2.2.1]alkenes that lead to the cleavage of the C-O bond instead of the N-O bond. Different acid catalysts were tested and it was found that pyridinium toluenesulfonate in methanol gave the best yields in the ring-opening reactions. The scope of the reaction was successfully expanded to include primary, secondary, and tertiary alcohol nucleophiles. Through X-ray crystallography, the stereochemistry of the product was determined which confirmed an SN2-like mechanism to form the ring-opened product.

| S-EPMC5753073 | biostudies-literature

catena-Poly[[diaqua-manganese(II)]-?-7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxyl-ato].

Project description:In the title polymer, [Mn(C(8)H(8)O(5))(H(2)O)(2)](n), the Mn(II) atom is in a distorted octa-hedral coordination mode, binding to the bridging O atom of the bicyclo-heptane unit, two O atoms from corresponding carboxyl-ate groups, one carboxyl-ate O atom from a symmetry-related bridging ligand and two water O atoms. This arrangement leads to the formation of polymeric chains propagating parallel to [001]. The crystal structure is stabilized by several O-H?O hydrogen-bonding inter-actions involving the coordinated water mol-ecules as donors and the carboxyl-ate O atoms as acceptors.

| S-EPMC2979419 | biostudies-literature

Regio- and stereoselective indium triflate-mediated nucleophilic ring-opening reactions of 3-aza-2-oxabicyclo[2.2.1]hept-5-ene and -[2.2.2]oct-5-ene systems.

Project description:Indium triflate-mediated nucleophilic ring-opening reactions of 3-aza-2-oxabicyclo[2.2.1]hept-5-ene and -[2.2.2]oct-5-ene systems with alcohols and water were investigated. Reactions of [2.2.1] bicyclic systems gave anti-1,2-, anti-1,4- and syn-1,4-ring-opened products with moderate to excellent regio- and stereoselectivity. When [2.2.2] bicyclic systems were subjected to similar reaction conditions, only anti-1,2 and anti-1,4-ring-opened products were obtained.

| S-EPMC2759854 | biostudies-literature

catena-Poly[[diaqua-nickel(II)]-?-7-oxabicyclo-[2.2.1]heptane-2,3-di-carboxyl-ato].

Project description:In the crystal structure of the title compound, [Ni(C(8)H(8)O(5))(H(2)O)(2)](n), the Ni(II) cation is in a Jahn-Teller-distorted octahedral coordination environment binding to two O atoms from water molecules, the bridging O atom of the bicycloheptane unit, two carboxylate O atoms from different carboxylate groups and one carboxylate O atom from a symmetry-related bridging ligand. The crystal structure is made up from layers propagating parallel to the bc plane.

| S-EPMC2969288 | biostudies-literature

Poly[[(2,2'-bipyridine)(?(3)-7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxyl-ato)cadmium] monohydrate].

Project description:The title compound, {[Cd(C(8)H(8)O(5))(C(10)H(8)N(2))]·H(2)O}(n), was obtained by the reaction of cadmium acetate with 2,2'-bi-pyridine and 7-oxabicyclo-(2.2.1)heptane-2,3-dicarb-oxy-lic anhydride. The Cd(II) atom is seven-coordinated in a distorted penta-gonal-bipyramidal configuration, defined by five O atoms from the carboxyl-ate groups of three 7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxyl-ato ligands and two N atoms from the 2,2'-bipyridine ligand. Two O atoms link two Cd(II) atoms, forming a dinuclear center: the Cd-O-Cd bridging angle is 110.19?(6)°. The polymeric structure extends along [100] and is linked by inter-molecular O-H?O hydrogen bonds involving the solvent water molecule. Extensive ?-? stacking exists between 2,2-bypiridine ligands along [010] with centroid-centroid distance of 3.650?(2)?Å

| S-EPMC3201414 | biostudies-literature

Triaqua-(7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxyl-ato-?O,O,O)cobalt(II) monohydrate.

Project description:The title complex, [Co(C(8)H(8)O(5))(H(2)O)(3)]·H(2)O, was synthesized by reaction of cobalt acetate with 7-oxabicyclo-[2.2.1]heptane-2,3-dicarb-oxy-lic anhydride (norcantharidin) in aqueous solution. In the mol-ecule, the Co(II) atom is six-coordinated in a distorted octa-hedral environment, binding to the bridging O atom of the bicyclo-heptane unit, to two O atoms from monodentate carboxyl-ate groups and to three water O atoms. The crystal structure is stabilized by several O-H?O hydrogen-bonding inter-actions involving both the coordinated and uncoordinated water mol-ecules as donors and the carboxyl-ate O atoms of neighbouring mol-ecules as acceptors.

| S-EPMC3212185 | biostudies-literature

Poly[bis-(1H-imidazole)(?(3)-7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxyl-ato)cadmium(II)].

Project description:The title compound, [Cd(C(8)H(8)O(5))(C(3)H(4)N(2))(2)](n), was synthesized by the reaction of 7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxylic anhydride, cadmium acetate and imidazole. The Cd(II) atom is seven-coordinated in a distorted penta-gonal-bipyramidal configuration by five O atoms from carboxyl-ate groups of three 7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxylate ligands and two N atoms from two imidazole ligands. The crystal structure is stabilized by N-H?O and C-H?O hydrogen-bonding and C-H?? inter-actions.

| S-EPMC2969310 | biostudies-literature

N-Carbamothioyl-amino-7-oxabicyclo-[2.2.1]hept-5-ene-2,3-dicarboximide.

Project description:The title compound, C(9)H(9)N(3)O(3)S, comprises a racemic mixture of chiral mol-ecules containing four stereogenic centres. The cyclo-hexane ring tends towards a boat conformation, while the tetra-hydro-furan ring and the dihydro-furan ring adopt envelope conformations. The dihedral angle between the thio-semicarbazide fragment and the fused-ring system is 77.20?(10)°. The crystal structure is stabilized by two inter-molecular N-H?O hydrogen bonds.

| S-EPMC3011812 | biostudies-other

The 7-aza-norbornane nucleus of epibatidine: 7-aza-bicyclo-[2.2.1]heptan-7-ium chloride.

Project description:7-Aza-bicyclo-[2.2.1]heptane (7-aza-norbornane) is a bridged heterocyclic nucleus found in epibatidine, the alkaloid isolated from the skin of the tropical poison frog Epipedobates tricolor. Since epibatidine is known as one of the most potent acetyl-choline nicotinic receptor agonists, a plethora of literature has been devoted to this alkaloid. However, there are no structural data on the unsubstituted 7-aza-norbornane, the parent bicyclic ring of epibatidine and its derivatives. We herein present the structural characterization of the 7-aza-bicyclo-[2.2.1]heptane parent ring as its hydro-chloride salt, namely 7-aza-bicyclo-[2.2.1]heptan-7-ium chloride, C6H12N+·Cl-. The compete cation is generated by a crystallographic mirror plane with the N atom lying on the mirror, as does the chloride anion. In the crystal, the cations are linked to the anions by N-H?Cl hydrogen bonds, which generate [001] chains.

| S-EPMC5588587 | biostudies-literature

N-(4-Chloro-phen-yl)-7-oxabicyclo-[2.2.1]hept-5-ene-2,3-dicarboximide.

Project description:In the title racemic compound, C(14)H(10)ClNO(3), which contains four stereogenic centres, the cyclo-hexane ring tends towards a boat conformation, while the tetra-hydro-furan and dihydro-furan rings adopt envelope conformations. The dihedral angle between the mean planes of the pyrrolidine-2,5-dione unit and the 4-chloro-phenyl ring is 49.0?(2)°.

| S-EPMC3011550 | biostudies-other

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