Anionic Rearrangement Research Articles

Synthesis of Enantiopure tert-Butanesulfinamide from tert-Butanesulfinyloxazolidinone

A three-step procedure for the preparation of enantiopure tert-butanesulfinamide 6 in 51% overall yield is described starting from (1R,2S)-N-Cbz-1,2-diphenylaminoethanol. The key step is the reaction of tert-butylmagnesium chloride with N-Cbz-4,5-diphenyl-1,2,3-oxathiazolidine-2-oxide 2 to afford the optical pure tert-butylsulfinyl-4,5-diphenyl-1,3-oxazolidinone 5 via an 1,5-alkoxy anion rearrangement, which is then subject to ammonia hydrolysis with LiNH(2) in liquid ammonia to give (R)-tert-butanesulfinamide 6.

The Anionic Phospho‐Fries Rearrangement

AbstractFor Abstract see ChemInform Abstract in Full Text.

Unexpected Formation of the Arcyriacyanin System by Condensation of a 3‐Bromo‐4‐(indol‐3‐yl)maleimide with (2‐Nitrophenyl)acetates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Application of Directed Metalation in Synthesis. Part 6. A Novel Anionic Rearrangement under Directed Metalation Conditions Leading to Heteroannulation.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Theoretical Study on the Rearrangement of β-OH and γ-OH in ESI Mass Spectrometry by N-Phosphorylation

The β-OH group is more active than γ-OH in many processes, such as the catalysis of the active site in enzymes and the N→O rearrangement of N-phosphoryl amino acids in negative-ion electrospray ionization mass spectrometry. The pentacoordinate phosphoric intermediates are proposed and the rearrangement mechanisms are studied by ab initio and density functional calculations. The formation of the intermediates comprises a concerted route and two different stepwise pathways. The concerted route is more favored. The cleavage of the P-N bond is the rate-determining step and is favored by the proton transfer. For the rearrangement of dimethoxyl phosphoryl serine anion and homoserine anion, the activation energies are 91.2 and 156.9 kJ/mol at the B3LYP/6-31+G(d,p) level, respectively. Therefore, the β-OH group is predicted to be more active than γ-OH and the result is in good agreement with the experiments.

Application of directed metalation in synthesis. Part 6: A novel anionic rearrangement under directed metalation conditions leading to heteroannulation*1

A short and efficient synthesis of condensed 1,4-oxathiin-2-ones from easily available phenols is described. The key step in this synthesis is a hitherto unreported anionic rearrangement under directed metalation conditions. The rearrangement occurs after side chain deprotonation of a methyl sulfanyl group by an O-carbamate directed metalating group and the reaction mixture is kept at room temperature for 8–12 h. Acid-mediated cyclisation of the rearranged product affords [1,4]oxathiin-2-one.

Application of directed metalation in synthesis. Part 6: A novel anionic rearrangement under directed metalation conditions leading to heteroannulation

A short and efficient synthesis of condensed 1,4-oxathiin-2-ones from easily available phenols is described. The key step in this synthesis is a hitherto unreported anionic rearrangement under directed metalation conditions. The rearrangement occurs after side chain deprotonation of a methyl sulfanyl group by an O-carbamate directed metalating group and the reaction mixture is kept at room temperature for 8–12 h. Acid-mediated cyclisation of the rearranged product affords [1,4]oxathiin-2-one.

Certain applications of heteroatom directed ortho-metalation in sulfur heterocycles

Manifold uses of heteroatom directed ortho-metalation which is responsible for its wide application in aromatic and heteroaromatic chemistry include regiocontrolled introduction of substitutents in aromatic or heteroaromatic ring and manipulation of introduced functionalities leading to chain extension and ring annulation. Metalated compounds also undergo a variety of anionic rearrangements providing synthetic strategies to target molecules. In this article work carried out in the authors’ laboratory on the application of this methodology in the field of sulfur heterocycles is reviewed.

Unexpected Formation of the Arcyriacyanin System by Condensation of a 3-Bromo-4-(indol-3-yl)maleimide with (2-Nitrophenyl)acetates

The reaction of an N-protected 3-bromo-4-(indol-3-yl)maleimide with methyl (2-nitrophenyl)acetates in the presence of base affords condensed cycloheptatriene derivatives which can be transformed into arcyriacyanin-type alkaloids. The unusual reaction sequence implies a heptatrienyl–cycloheptadienyl anion rearrangement followed by a 1,5-sigmatropic shift to yield the thermodynamically more stable cycloheptatriene derivative.

Application of Directed Metalation in Synthesis. Part 5. Synthesis of Condensed Sulfur—Oxygen Heterocycle via Novel Anionic Rearrangement—Cyclization.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Anion Rearrangements in Fluorinated Nd2CuO3.5.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient Preparation of Polysubstituted Naphthyl Phenyl and Dinaphthyl Ketones from Naphthalenic Esters by Anionic Homo-Fries Rearrangement.

The anionic homo-Fries rearrangement of naphthalenic esters can be effected in good yield to provide regiocontrolled access to complex diaryl ketones.

Indium(I)-Mediated, Tandem Carbonyl Addition-Oxy-Cope Rearrangement of γ-Pentadienyl Anions to Cyclohexenones and Conjugated Aromatic Ketones

Treatment of 5-bromopenta-1,3-diene with indium metal in the presence of α,β-unsaturated ketones results in initial γ-pentadienylation to generate the hydroxy-1,4-diene. In the case of aromatic conjugated ketones or cyclohexenones the indium alkoxide undergoes spontaneous oxy-Cope rearrangement to afford the 1,4-addition product. The second double bond is required for this [3,3] sigmatropic rearrangement as allyl groups fail to under go this in situ rearrangement. This behavior is consistent with an indium(I) pentadiene species and appears to be the first example of an indium-mediated oxy-Cope rearrangement.

Application of Directed Metalationin Synthesis. Part 5:Synthesis of CondensedSulfur-Oxygen Heterocycle via Novel Anionic Rearrangement-Cyclisation

Introduction of the methyl sulfanyl function in the ortho-position to O-carbamate functionality under standard directed metalation condition was followed by side-chain deprotonation with sec-butyl lithium at -78 °C. Upon warming to room temperature, the deprotonated species underwent intramolecular anionic rearrangement to afford N,N-diethyl-2-hydroxyarylthioacetamides. The rearranged products were cyclised with hot glacial acetic acid to afford condensed oxathiin-2-ones in excellent yields.

Anion Rearrangements in Fluorinated Nd2CuO3.5

Nd 2 CuO 3.5 , a derivative of Nd 2 CuO 4 with anion-deficient (CuO 1.5 □ 0.5 ) layers, has been fluorinated with XeF 2 at temperatures between 100 and 400 °C. Samples fluorinated at 200-300 °C exhibit superconductivity with critical temperatures of 6-11 K. Electron microscopy investigations revealed a complicated microstructure in both the initial and fluorinated phases. Nd 2 CuO 3.5 is characterized by the presence of numerous twins which are caused by the lowering of the symmetry after a topotactic oxygen removal from the parent Nd 2 CuO 4 phase. Fluorination at 200°C leads to an increase of the formal copper valence and to a restoration of the T'-type structure. It is suggested that fluorine replaces oxygen in the Nd 2 O 2 slab and the released oxygen atoms migrate into the (CuO 1.5 □ 0.5 ) layers thus forming conducting (CuO 2 ) planes. This rearrangement shows a close resemblance to that previously found in fluorinated A 2 CuO 3 (A = Ca, Sr). Local areas of fluorinated phases with larger values of the c parameter were found in the matrix of T' phase. At 300 °C the monoclinic Nd 2 Cu(O,F) 5 phase is also formed (a ≃ 13.2 A, b ≃ 5.5 A, c ≃ 5.8 A, β ≃ 92°, space group C2/c) with a chainlike ordering of the empty and filled anion positions in the Nd 2 (O,F) 3 blocks and buckled (CuO 2 ) planes due to a tilt of the Cu(O,F) 6 octahedra.

A New Type of Anionic Rearrangement in Metalated Benzylhydrazines

Metalation of N,N-dibenzyl-N′-(trimethylsilyl)hydrazine with organyllithium and -magnesium compounds led to the migration of the benzyl group, and the deprotonation of Si−Me groups was observed. The syntheses and crystal structures of Bzl2N−NH2, [Bzl(Li)N−N(SiMe3)Bzl]2, and [Mg[BzlN−N(SiMe2CH2)Bzl]2 are presented. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

A New Type of Anionic Rearrangement in Metalated Benzylhydrazines

Metalation of N,N-dibenzyl-N′-(trimethylsilyl)hydrazine with organyllithium and -magnesium compounds led to the migration of the benzyl group, and the deprotonation of Si−Me groups was observed. The syntheses and crystal structures of Bzl2N−NH2, [Bzl(Li)N−N(SiMe3)Bzl]2, and [Mg[BzlN−N(SiMe2CH2)Bzl]2 are presented. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Efficient Preparation of Polysubstituted Naphthyl Phenyl and Dinaphthyl Ketones from Naphthalenic Esters by Anionic Homo-Fries Rearrangement

The anionic homo-Fries rearrangement of naphthalenic esters can be effected in good yield to provide regiocontrolled access to complex diaryl ketones.

Stereoselective Lateral Functionalization of Monosubstituted [2.2]Paracyclophanes by Directedortho-Metalation−Homologous Anionic Fries Rearrangement

Stereoselective Lateral Functionalization of Monosubstituted [2.2]Paracyclophanes by Directedortho-Metalation−Homologous Anionic Fries Rearrangement

Preparation of TADOOH, a Hydroperoxide from TADDOL, and Use in Highly Enantioface- and Enantiomer-Differentiating Oxidations

Replacement of one OH group in TADDOL (=α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5-dimethanol) by an OOH group gives a stable, crystalline chiral hydroperoxy alcohol TADOOH (={(4R,5R)-5-[(hydroperoxydiphenyl)methyl]-2,2-dimethyl-1,3-dioxolan-4-yl}diphenylmethanol) 3, the crystal structure of which resembles those of numerous other TADDOL derivatives (Fig. 2). The new hydroperoxide was tested as chiral oxidant in three types of reactions: the epoxidation of enones with base catalysis (Scheme 2), the sulfoxidation of methyl phenyl sulfide (Scheme 3), and the Baeyer-Villiger oxidation of bicyclic and tricyclic cyclobutanones, rac-10a – d with kinetic resolution (Scheme 4, Fig. 3, and Table). Products of up to 99% enantiomer puritiy were isolated (the highest values yet observed for oxidations with a chiral hydroperoxide!). Mechanistic models are proposed for the stereochemical courses of the three types of reactions (Schemes 5 and 6, and Fig. 4). Results of AM1 calculations of the relative transition-state energies for the anionic rearrangements of the exo Criegee adducts of TADOOH to the enantiomeric bicyclo[3.2.0]heptan-6-ones are in qualitative agreement with the observed relative rates (Table and Fig. 5).