Asymmetric synthesis of drug-like functionalized spiro[chroman-3,3'-indolin]-2'-ones 5 containing three contiguous stereocenters with high diastereo- and enantioselectivities was achieved using the reflexive-Michael (r-M) reaction of unmodified hydroxyenals 1 with various (E)-3-alkylideneindolin-2-ones 2 in the presence of (R)-DPPOTMS/AcOH (R)-3/4b as a catalyst at room temperature. Chiral spir...

The privileged spiro[pyrrolidin-3,3'-oxindole] derivatives exhibit important biological activities. An enantioselective organocatalytic approach to the rapid synthesis of spiro[pyrrolidin-3,3'-oxindole] derivatives with high enantiopurity and structural diversity is described. The asymmetric catalytic three-component 1,3-dipolar cycloaddition of a broad range of methyleneindolinones with aldehy...

Facile aerial oxidation is a general feature of guanine ribo- and 2'-deoxyribonucleosides that are substituted at the 8-position by an aminoaryl group. In previous work, it had been suggested that two of the major oxidation products are a pair of diastereomers having a spiro structure. These were presumed to be related by a chiral difference at the spiro carbon atom. The pattern of the oxidativ...

An enantioselective phosphine-catalyzed transformation has been developed for the synthesis of chiral cyclobutene triesters and fluorinated spirocyclic compounds. The strategy involved a P(III)/P(V) redox cycling process, via in situ reduction phosphine oxide with phenylsilane. This catalytic methodology enabled functionalized cyclobutenes (24 examples, up to 94% ee). On occasion extension this...

In the present work, we describe a convenient synthesis of spiro-fused D-fructo- and D-psico-configurated oxazoline ligands and their application in asymmetric catalysis. The ligands were synthesized from readily available 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-fructopyranose and 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-psicopyranose, respectively. The latter compounds were partially de...

Efficient optimization procedures in chiral catalysis are usually linked to a straightforward strategy to access groups of structurally similar catalysts required for fine-tuning. The ease of building up such ligand libraries can be increased when the structure-modifying step (introduction of a substituent) is done at a later stage of the synthesis. This is demonstrated for the extended family ...

Radical-radical cross coupling reactions of photoexcited 9-fluorenones have been accomplished for the first time, leading to the synthesis of 9-alkyl, pyrollidinyl and spiro-THF derivatives of 9-fluorenones. The method also reveals, for the first time, the behaviour of ketyl radicals in decarboxyaltive alkylation and ring expansion reactions.

Association of enantiopure TRISPHAT anion (1) with chiral spiro [Cu(LL')2] complexes (LL' = 2-R-phen, 2, 6-R-bpy, 3, and 2-iminopyridine, 4) leads to an efficient NMR enantiodifferentiation. Variable temperature 1H NMR spectroscopy has been used to determine the isomerisation kinetics of these pseudo-tetrahedral complexes and to evaluate their configurational stability; the latter depending on ...