Search

N-Phenyl-C-chromonyl nitrones 1 and the allenoate zwitterion 2, generated by addition of phosphine to acetylenedicarboxylates, undergo a cascade reaction sequence involving an unprecedented [5+3] annulation followed by deoxygenative rearrangement leading to dihydropyridine-fused benzopyrones. Unusual electronic control by the N-substituents of 1 directs the annulation pathway, leading to two different ring-systems. [ABSTRACT FROM AUTHOR]

The article focuses on the crystallization of the compound tris(cyclohexylmethyl)amine. The compound formed is a sterically hindered amine with three cyclohexane rings having chair conformations. In the experiment a solution of cyclohexene in dioxane, methanol and glacial acetic acid in the presence of urea was treated under hydroaminomethylation conditions. The mixture was extracted with ethyl acetate.

The chiral title compound, C17H20ClNO5, arose as a side product during the synthesis of novel furanomycin derivatives. The stereochemistry at the bicyclic core is consistent with a halolactonization step. The five-membered rings are nearly perpendicular to each other [torsion angle at the common bond: −88.3 (3)°]. [ABSTRACT FROM AUTHOR]

The title compound, C12H15ClF3NO4, is a side product in a synthesis of novel furanomycin derivatives. The stereochemistry at the bicyclic core is consistent with a halolactonization step. However, racemization also occurred via an unknown mechanism. The five-membered rings are nearly perpendicular to each other [torsion angle at the common bond: −95.6 (2)°]. [ABSTRACT FROM AUTHOR]

In the title compound, C40H32N2O2P2, used as a nixantphos-type ligand in homogeneous catalysis, the central phenoxazine ring system deviates markedly from planarity, the dihedral angle between the two halves being 38.14 (3)°. The intra­molecular P⋯P distance is 4.2400 (7) Å. [ABSTRACT FROM AUTHOR]

A cascade double-annulation strategy employing diverse pairs of zwitterions with 3-formylchromones is presented that provides stereoselective access to complex tetracyclic benzopyrones. Different zwitterions incorporated different rings that include aza-, oxa-, and carbocycles fused to a common benzopyrone scaffold and in the process created three contiguous chiral centers including an all-carbon-quaternary center with high efficiency and excellent stereoselectivity. [ABSTRACT FROM AUTHOR]

Abstract: The pentacyclic spirotryprostatin scaffold embodies an oxindole with an all-carbon quaternary stereocenter. The scaffold can efficiently be accessed in a one-pot reaction sequence consisting of a highly enantioselective 1,3-dipolar cycloaddition, N-acylation of the resulting stereochemically complex 3,3′-pyrrolidinyl-spirooxindole core with Fmoc-proline and spontaneous ring closure upon N-deprotection. [Copyright &y& Elsevier]

In the title compound, C40H33NO3P2, used as a nixantphos-type ligand in homogeneous catalysis, the central phenoxazine ring system is nearly planar. The most important feature of the mol­ecule is the intra­molecular P⋯P distance of 4.2346 (13) Å. The angles involving the P atoms are in the range 100.90 (13)–103.40 (16)°. [ABSTRACT FROM AUTHOR]