β-oxy-α-diazo carbonyl compounds. II. conversion to chiral α-oxy-α′-diazo ketones and photochemical reaction

Lopez‐Herrera, F. J.; Sarabia-García, F.

doi:10.1016/s0040-4039(00)76663-9

Cited by 17 publications

(9 citation statements)

References 30 publications

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“…Preparation and decomposition reaction of hydroxycycloalkyl diazoacetones. Although DAA (1) can be easily obtained by acylation of diazomethane (15) with acetylchloride (16), its isolation from the crude reaction mixture is shown to be inefficient following the poor detailed experimental More recently, López-Herrera and Sarabia-García studied the photochemical decomposition of α-diazo ketone 3b prepared from 2,3-O-isopropylidene-D-glyceraldehyde (2b) and diazoacetone (DAA, 1b) to determine those factors that favor the Wolf rearrangement over the 1,2-hydride shift (Scheme 1B) [12][13][14]. In line with this work, Wang and co-workers reported a mechanistic study on the decomposition reaction of β-(N-tosyl)amino diazocarbonyl compounds 3c [15][16][17].…”

Section: Resultsmentioning

confidence: 99%

“…In 2017, Cleary et al described the Lewis acid-catalyzed vinyl cation rearrangement of α-diazo-β-hydroxy ketones 1f by 1,2-shift and subsequent C-H insertion at non-activated γ C-H bond [21]. This reaction allows the preparation of synthetic versatile bicyclic cyclopentenones fused with seven-and eightmembered rings (14) (Scheme 1F) [21].…”

Section: Introductionmentioning

confidence: 99%

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BF3·Et2O-Promoted Decomposition of Cyclic α-Diazo-β-Hydroxy Ketones: Novel Insights into Mechanistic Aspects

et al. 2018

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We report novel insights into the cascade rearrangement of destabilized vinyl cations deriving from the BF3·Et2O-induced decomposition of cyclic α-diazo-β-hydroxy ketones in turn prepared by aldol-type condensation of cycloalkanones with diazoacetone. Complexation of the hydroxy group of the α-diazo-β-hydroxy compound with the Lewis acid is the first event, followed by the generation of the cycloalkanylidenediazonium salt that, after nitrogen loss, produces the highly reactive vinyl cation. The subsequent ring expansion results in the formation of a cycloalkenyl vinyl cation that affords the allylic cation by 1,2-methylene shift and ring contraction. The cation can then trap the solvent, the fluoride or the hydroxide released from the [BF3OH]− to afford different reaction products. The effect of both solvent and substrate ring size on products types and ratios were analyzed and discussed from a mechanistic point of view.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

BF3·Et2O-Promoted Decomposition of Cyclic α-Diazo-β-Hydroxy Ketones: Novel Insights into Mechanistic Aspects

et al. 2018

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“…First, the experiments were carried out at 274 K and second, the shifts (especially for the substituted system) involved movements of several heavy atoms (see later). The oxirene species [20,30,33,35,40] has not been taken into account since the product distribution does not show any hint of its role in the processes as probably has when the diazo and carbonyl groups are in inverted positions [37]. Nevertheless, theoretical studies are in progress to elucidate its participation.…”

Section: Regular Articlementioning

confidence: 99%

“…Particularly, the isomerisation reactions of ketocarbenes are presently the subject of extensive studies [20±35]. LoÂ pez-Herrera and Sarabia [36,37] departing from D-glyceraldehyde have recently designed a route aimed at synthesising 1-methyl-2-hydroxy synthons on asymmetric carbons, which constitute the skeleton of some antibiotic macrolides. The synthesis utilised the wol rearrangement (WR) (Scheme 1) of a-ketodiazo compounds as its principal reaction step.…”

Section: Introductionmentioning

confidence: 99%

The influence of protecting the hydroxyl group of β-oxy-α-diazo carbonyl compounds in the competition between Wolff rearrangement and [1,2]-hydrogen shift. Density functional theory study and topological analysis of the charge density

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Lopez‐Herrera

et al. 2000

Theoretical Chemistry Accounts: Theory, Computation, and Modeli

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The in¯uence of protecting the hydroxyl group of a b-oxy-a-diazo carbonyl compound on the competition between the Wol rearrangement (WR) and the [1,2]-hydrogen shift (HS) was investigated theoretically. Stationary points on the potential-energy surface were located with the B3LYP density functional and the 6-31G** basis set. For the basic system geometry optimisations at B3LYP/6-311+G** were performed to validate the reliability of the B3LYP/6-31G** calculations. Singlepoint energy calculations were carried out at the B3LYP/ 6-311+G** level on the B3LYP/6-31G**-optimised geometries. Further insight into the processes was achieved with the aid of the theory of``atoms in molecules'' of Bader. The calculated energy barriers qualitatively predicted the yields of HS and WR obtained experimentally. In order to rationalise the calculated energy barriers, it was necessary to take into account not only the electronegativity of the protective groups but also the alignment of the migrating groups with the depletion sites at the carbene centre. Further, when the hydroxyl group was not protected the existence of an intramolecular hydrogen bond played an important role in both HS and WR.

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“…One of the synthetic routes to the formation of 1-methyl-2-hydroxy synthons, which constitute the skeleton of some antibiotic macrolides, proceeds through the stereoselective Wolff rearrangement of intermediate ketocarbenes obtained from the photolytical cleavage of β-oxy-α-diazo compounds . However, the competitive 1,2-H-shift reaction becomes the most favored pathway in the case of β-hydroxy-α-diazo compounds, rendering a 100% yield for the formation of a vinyl-ketone product …”

Section: Introductionmentioning

confidence: 99%

Competition between Wolff Rearrangement and 1,2-Hydrogen Shift in β-Oxy-α-ketocarbenes: Electrostatic and Specific Solvent Effects

et al. 1999

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A quantum chemical investigation of the solvent effects on the competition between the Wolff transposition and 1,2-H-shift in -hydroxy-ketocarbenes in aqueous solution was carried out at the B3LYP/6-31G** level of theory. The inclusion of solvent effects by means of a continuum model was not able to reproduce the experimental yields. Then, a semidiscrete approach consisting of solute-solvent association complexes embedded in a dielectric continuum was used to estimate the solvent influence on the Gibbs activation energies. The calculated ∆G are 0.88 and 4.94 kcal/mol for the 1,2-H-shift and the Wolff transposition processes, respectively, thus rendering a 100% yield for the formation of the vinyl-ketone product in agreement with experiment. The TS for the 1,2-H-shift process is preferentially stabilized by solvent due to a H-bond between the migrating hydrogen and one of the water molecules in the association complex. This effect of solvent is analyzed by means of hybrid QM/MM calculations using a classical description of water molecules with the TIP3P model.

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β-oxy-α-diazo carbonyl compounds. II. conversion to chiral α-oxy-α′-diazo ketones and photochemical reaction

Cited by 17 publications

References 30 publications

BF3·Et2O-Promoted Decomposition of Cyclic α-Diazo-β-Hydroxy Ketones: Novel Insights into Mechanistic Aspects

BF3·Et2O-Promoted Decomposition of Cyclic α-Diazo-β-Hydroxy Ketones: Novel Insights into Mechanistic Aspects

The influence of protecting the hydroxyl group of β-oxy-α-diazo carbonyl compounds in the competition between Wolff rearrangement and [1,2]-hydrogen shift. Density functional theory study and topological analysis of the charge density

Competition between Wolff Rearrangement and 1,2-Hydrogen Shift in β-Oxy-α-ketocarbenes: Electrostatic and Specific Solvent Effects

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