Lithium cadmate-mediated deprotonative metalation of anisole: experimental and computational study

International audienceLithium cadmates bearing different ligands were compared with efficient (TMP)(3)CdLi (TMP = 2,2,6,6-tetramethylpiperidino) for their ability to deprotometalate anisole. The generated arylcadmates were evidenced using I(2). The results show that it is possible to replace only one of the TMP (with a piperidino, a diisopropylamino, a butyl, or a sec-butyl) without important yield drop. In the light of DFT calculations, reaction pathways were proposed for the deprotocadmations of anisole using a triamino, an alkyldiamino, and an aminodialkyl cadmat

Diastereoselective deprotonative metalation of chiral ferrocene derived acetals and esters using mixed lithium-cadmium and lithium-zinc combinations

International audienceIn situ bimetal combinations, and notably those prepared from MCl2(radical dotTMEDA) (M=Zn, Cd; TMEDA=N,N,N′,N′-tetramethylethylenediamine) and Li(TMP) (3 or 4 equiv, TMP=2,2,6,6-tetramethylpiperidino), were screened for their ability to diastereoselectively deprotonate ferrocenes bearing a chiral group. The ferrocene carboxylate generated from diacetone-d-glucose afforded the corresponding 2-iodo derivative in 74% yield with 90% de (SP diastereoisomer) using the base generated from CdCl2 and Li(TMP) (3 equiv), and in 85% yield with 91% de (SP diastereoisomer) through a double asymmetric induction using a chiral lithium-zinc base generated from ZnCl2*TMEDA and lithium (R)-bis(1-phenylethyl)amide (4 equiv). In contrast, using a combination prepared from ZnCl2 and Li(TMP) (4 equiv) with the ferrocene carboxylate obtained from 6-(tert-butoxycarbonylamino)-6-deoxy-3-O-methyl-1,2-O-isopropylidene-α-d-glucofuranose led to the RP-iodo derivative in 57% yield after separation. Suzuki coupling was performed satisfactorily on the isolated SP and RP diastereoisomer iodoesters

Synthesis of both enantiomers of ferrocene[1,2-c]1H-quinolin-2-one by diastereoselective deproto-zincation of sugar-derived ferrocene esters

This research has also been performed as part of the Indo-French "Joint Laboratory for Sustainable Chemistry at Interfaces". The calculations were performed by using the RIKEN Integrated Cluster of Clusters (RICC) facility.International audienceDiastereoselective deproto-metallation of several sugar-derived ferrocene esters using lithium-zinc bases was studied. While bis[(R)-1-phenylethyl]amino as ligand afforded the diacetone-D-glucose-based (SP)-2-iodoferrocene ester in 91% de after iodination, the RP was synthesized from α-D-glucofuranose using 2,2,6,6-tetramethylpiperidino as ligand. Both (RP)- and (SP)-ferrocene[1,2-c]1H-quinolin-2-one were reached by subsequent cyclizing coupling, albeit their racemization was noted

Structural effects in lithiocuprate chemistry:the elucidation of reactive pentametallic complexes

TMPLi (TMP=2,2,6,6-tetramethylpiperidide) reacts with Cu(I) salts in the presence of Et(2)O to give the dimers [{(TMP)(2)Cu(X)Li(2)(OEt(2))}(2)] (X=CN, halide). In contrast, the use of DMPLi (DMP=cis-2,6-dimethylpiperidide) gives an unprecedented structural motif; [{(DMP)(2)CuLi(OEt(2))}(2)LiX] (X=halide). This formulation suggests a hitherto unexplored route to the in situ formation of Gilman-type bases that are of proven reactivity in directed ortho cupration

Construction of Functionalized ortho-Naphthoquinone Methides via Site-Selective Ring Opening of 1-Siloxy-1,4-epoxy-1,4-dihydronaphthalenes

1-Siloxy-4-(benzyloxy)methyl-1,4-epoxy-1,4-dihydronaphthalenes, generated from benzynes and furans, underwent automatic site-selective ring opening because of the synergetic effect of the steric strain of the 1,4-epoxy moiety and the electron-donating ability of the siloxy group on the acetal structure to afford the precursors of ortho-naphthoquinone methides (o-NQMs). Subsequent Lewis acid-facilitated o-NQM formation and annulation with olefins afforded multi-fused heterocycles. Notably, the consecutive hexacyclic skeleton of rubioncolin B was constructed via solvent-dependent regioselective annulation of naphthofuran derivatives.This is the peer reviewed version of the following article: Aijima T., Komagawa S., Akai S., et al. Construction of Functionalized ortho-Naphthoquinone Methides via Site-Selective Ring Opening of 1-Siloxy-1,4-epoxy-1,4-dihydronaphthalenes. Advanced Synthesis and Catalysis 365, 3981 (2023), which has been published in final form at https://doi.org/10.1002/adsc.202300968. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited

Mechanistic Origin of Chemo- and Regioselectivity of Nickel-Catalyzed [3 + 2 + 2] Cyclization Reaction

A density functional theory (DFT) study was performed to elucidate the mechanism of the Ni-catalyzed [3 + 2 + 2] cyclization reaction of cyclopropylideneacetate with two alkynes. A systematic search showed that the nature of the alkynes determines the choice between two reaction pathways and hence the regioselectivity. Strongly electron-deficient acetylenes preferentially afford 2,5-disubstituted products via nickelacyclopentadienes generated by [2 + 2] cocyclization, whereas normal alkynes afford 3,4- or 3,5-products via an unprecedented pathway involving a [3 + 2] nickelacycle intermediate

Control of a Chiral Property of a Calix[3]aramide: The Racemization Suppressed by Intramolecular Cyclic Hydrogen Bonds and DMSO–H₂O System-Induced Spontaneous Resolution

A calix[3]­aramide has been synthesized bearing three triphenylphosphinic amide moieties, which formed intramolecular cyclic hydrogen bonds that suppressed its <i>cone</i>/<i>partial cone</i> inversion. The intramolecular cyclic hydrogen bonds were disrupted by DMSO, and the insertion of H₂O into the hydrogen bonds triggered the spontaneous resolution of the calix[3]­aramide. Within a chiral environment, such as that afforded by the presence of optically active 2-butanol, the calix[3]­aramide underwent a symmetry breaking crystallization process

Deprotonative metalation of substituted benzenes and heteroaromatics using amino/alkyl mixed lithium-zinc combinations.

International audienceDifferent homoleptic and heteroleptic lithium-zinc combinations were prepared, and structural elements obtained on the basis of NMR spectroscopic experiments and DFT calculations. In light of their ability to metalate anisole, pathways were proposed to justify the synergy observed for some mixtures. The best basic mixtures were obtained either by combining ZnCl(2).TMEDA (TMEDA=N,N,N',N'-tetramethylethylenediamine) with [Li(tmp)] (tmp=2,2,6,6-tetramethylpiperidino; 3 equiv) or by replacing one of the tmp in the precedent mixture with an alkyl group. The reactivity of the aromatic lithium zincates supposedly formed was next studied, and proved to be substrate-, base-, and electrophile-dependent. The aromatic lithium zincates were finally involved in palladium-catalyzed cross-coupling reactions with aromatic chlorides and bromides