Construction of Spiro[pyrrolidine‐3,3′‐oxindoles] − Recent Applications to the Synthesis of Oxindole Alkaloids

Transition metal-catalyzed cross-coupling reactions of alkyl metals and aryl halides or pseudohalides have emerged as a powerful methodology for the formation of Csp3-Csp2 bonds over the past decades.1 However, significant attention has also been focused on Pdand Ni-catalyzed Csp3-Csp2 bond-forming reactions that involve aryl metals and haloalkyl compounds lacking -hydrogen atoms as cross-coupling partners.2 In contrast, until a few years ago, few examples were reported in the literature concerning transition metalcatalyzed reactions of aryl metals with functionalized alkyl halides including R-halocarbonyl compounds and R-bromosulfones bearing -hydrogen atoms,3 and a single example of Pd-catalyzed cross-coupling reaction of aryl metals and unfunctionalized alkyl halides bearing -hydrogen atoms had been described.4 Only in recent years, successful procedures for the Pd-,5 Ni-,6 Rh-,7 Fe-,8 V-,9 Co-,10 and Cu-catalyzed11 cross-coupling reactions of aryl metals and unfunctionalized alkyl halides bearing -hydrogen atoms have been developed.12 Nevertheless, new, effective, and more environmentallybenignmethodologiesfortheformationof(cyclo)alkyl-aryl bonds, which require a reduced number of synthetic operations, have emerged as valuable alternatives to the conventional cross-coupling reactions. These methodologies (Scheme 1) are based on transition metal-catalyzed simple or 2-fold C-H bond functionalization according to the following approaches: (a) highly regioselective Pd-catalyzed direct arylation reactions of unactivated sp3-hybridized C-H bonds with aryl halides (eq a, Scheme 1);13 (b) Pd-catalyzed direct alkylation reactions of aryl C-H bonds with alkyl metals (eq b, Scheme 1);14 Au-15 or Pdcatalyzed16 direct alkylation reactions of aryl C-H bonds with alkyl halides or pseudohalides (eq c, Scheme 1); (d) Pd-catalyzed arylations of unactivated sp3-hybridized C-H bonds with aryl metals (eq d, Scheme 1);14c (e) Pd-, Ru-, or Cu-catalyzed cross-coupling reactions of sp3-hybridized C-H bonds with arylboronic acids using air as oxidant (eq d, Scheme 1);17 and (f) cross-dehydrogenative coupling of alkyl and aryl C-H bonds (eq e, Scheme 1).18 Finally, great attention, particularly in the past decade, has also been focused on the design, development, and application of transition metal-catalyzed coupling reactions of aryl halides and pseudohalides with a wide variety of substrates containing activated sp3-hybridized C-H bonds (eq f, Scheme 1). A mini-review on this topic was published by Scolastico and Poli in 1999,19 and three excellent reviews that concern the results obtained in this rapidly growing area of extensive research by the groups of Miura, Natsume, Hartwig, and Buchwald up to the end of 2002 were published by Miura,20 Hartwig,21 and Lloyd-Jones22 a few years later. However, the reviews by Miura20 and Hartwig21 were limited in that they fundamentally emphasized the author’s own work and * To whom correspondence should be addressed. E-mail: rossi@dcci.unipi.it. Chem. Rev. 2010, 110, 1082–1146 1082

Transition metal-catalyzed direct arylation of substrates with activated sp3-hybridized C-H bonds and some of their synthetic equivalents with aryl halides and pseudohalides.

Palladium-Catalyzed α-Arylation of Ketones

Sulfur-doped disordered carbon is facilely synthesized and investigated as an anode for sodium ion batteries. Benefiting from the high sulfur doping (∼26.9 wt%), it demonstrates a high reversible capacity of 516 mA h g−1, excellent rate capability as well as superior cycling stability (271 mA h g−1 at 1 A g−1 after 1000 cycles).

A high performance sulfur-doped disordered carbon anode for sodium ion batteries

Asymmetric catalysts, either chemical or biological, effect the reactions of enantiomeric substrates at unequal rates, allowing for the kinetic resolution of racemates. The asymmetric reaction of chirally labile compounds capable of undergoing in situ racemization can, in principle, afford a single stereoisomer in 100% ee and in 100% yield. The second-order reaction provides a powerful tool for the stereoselective synthesis of chiral compounds, as exemplified by, among others, the biochemical hydrolysis of hydantoins or oxazolinones and microbial reductions or BINAP–Ru(II) catalyzed hydrogenation of certain α-substituted β-keto esters. Such transformations are characterized by the presence of parallel reactions interrelated by the stereoinversion of the enantiomeric substrates. The efficiency is decisively affected by the kinetic parameters, particularly the relative rates of the stereoinversion and reaction as well as the intrinsic stereochemical parameters of the catalyst and substrate. Such stereoselec...

Stereoselective Organic Synthesis via Dynamic Kinetic Resolution

A mild and efficient SRN1 approach to diaryl sulfides from arenediazonium tetrafluoroborates

Vibrational spectra and assignment of poly-(p-phenylene sulfide) and its oligomers

Static and dynamic stereochemistry of the hydrocarbon comprising a phenyl ring bearing two α-naphthyl substituents in the ortho positions, i.e., 1,2-di-(4-methyl-naphth-1-yl)-benzene 1, has been studied by a combination of variable temperature NMR, cryogenic HPLC, and MM calculations. Whereas in solution both syn (meso) and anti (chiral) forms were observed and the corresponding interconversion barrier was determined (ΔG⧧ = 19.5 kcal mol-1), only the diastereoisomer anti was found to be present in the crystalline state (X-ray diffraction). When the molecule is rendered asymmetric by introduction of a nitro group in the phenyl ring as in 1,2-di-(4-methyl-naphth-1-yl)-4-nitrobenzene 2, the chiral syn and anti diastereoisomers are simultaneously present both in solution and in the solid state, albeit in different proportions. Cryogenic chromatography on a HPLC chiral stationary phase at −20 °C allowed the stereolabile diastereoisomers and the corresponding enantiomers to be separated.

Conformational studies by dynamic NMR. 86. Structure, stereodynamics, and cryogenic enantioseparation of the stereolabile isomers of o-dinaphthylphenyl derivatives.

Synthetic exploitation of the ring-opening of 3,4-dinitrothiophene. Access to 1,4-disubstituted 2,3-dinitro-1,3-butadienes and 2,3-butanedione dioximes

Marino Novi

Papers

A mild and efficient SRN1 approach to diaryl sulfides from arenediazonium tetrafluoroborates

Vibrational spectra and assignment of poly-(p-phenylene sulfide) and its oligomers

Conformational studies by dynamic NMR. 86. Structure, stereodynamics, and cryogenic enantioseparation of the stereolabile isomers of o-dinaphthylphenyl derivatives.

Synthetic exploitation of the ring-opening of 3,4-dinitrothiophene. Access to 1,4-disubstituted 2,3-dinitro-1,3-butadienes and 2,3-butanedione dioximes

Carbon-13 NMR study on the nature of resonance interactions in 4-substituted benzonitriles, acetophenones, and methyl benzoates