Rearrangement of Allylic Azides

Gagneux, André R.; Winstein, S.; Young, W. Glenn

doi:10.1021/ja01507a045

Cited by 190 publications

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“…This unexpected transformation can be rationalized by an initial insertion of the rhodium carbenoid into the adja- brates with its enol form 25 which then undergoes a subsequent [3,3]-sigmatropic shift with complete stereospecificity in a suprafacial manner [1][2][3][4][5] . The rearranged allylic azide intermediate 26 thus formed furnishes the observed 3(2H)-furanones via a keto-enol equilibration (Scheme 5).…”

Section: Resultsmentioning

confidence: 99%

“…Allylic azides are described as species co-existing in equilibrium between regioisomers [1][2][3] . In 1960, Gagneux, Winstein and Young reported that α-and γ-substituted allyl azides rapidly form an equilibrium mixture of the two isomers and the rate and equilibrium constants of this rearrangement were measured 1 .…”

Section: Introductionmentioning

confidence: 99%

“…In 1960, Gagneux, Winstein and Young reported that α-and γ-substituted allyl azides rapidly form an equilibrium mixture of the two isomers and the rate and equilibrium constants of this rearrangement were measured 1 . Two mechanisms can be postulated to rationalize this transformation: (1) a concerted, [3,3]-sigmatropic rearrangement (path A), in which the stereochemical integrity of the molecule is preserved and (2) a dissociative process involving ion-pair formation (path B), whereby the initial stereochemistry can be lost (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

“…Two mechanisms can be postulated to rationalize this transformation: (1) a concerted, [3,3]-sigmatropic rearrangement (path A), in which the stereochemical integrity of the molecule is preserved and (2) a dissociative process involving ion-pair formation (path B), whereby the initial stereochemistry can be lost (Scheme 1). It was noted that the rearrangement was remarkably insensitive to changes in solvent as well as to alkyl substitution [1][2][3] . These observations are indicative of very little charge separation in the transition state, and it is generally assumed that the equilibration occurs via a cyclic transition state (i.e., path A).…”

Section: Introductionmentioning

confidence: 99%

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Rhodium(II)-Catalysed Intramolecular O-H Insertion of alpha-Diazo-gamma-Azido-delta-Hydroxy-beta-Ketoesters: Evidence for a Novel Sigmatropic Rearrangement of an Allylic Azide Intermediate

Padwa¹,

Sá²

1999

J. Braz. Chem. Soc.

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3(2H)-Furanona-2-carboxilatos têm sido preparadas em bons rendimentos e seletividade moderada (d.e. ca 60%), a partir da reação de inserção de O-H intramolecular de δ-hidroxi-α-diazoésteres catalisada por Rh2(OAc)4. Observou-se que as furanonas 2,5-cis substituídas são formadas inicialmente na reação, sofrendo epimerização quando submetidas à cromatografia em sílica gel, fornecendo os isômeros 2,5-trans correspondentes. A decomposição de γ-azido-δ-hidroxi-α-diazoestéres catalisada por Rh2(OAc)4 também forneceu 3(2H)-furanona-2-carboxilatos. Estes compostos são formados a partir de transformações sequenciais, envolvendo primeiramente uma reação de inserção de O-H intramolecular, seguido de um rearranjo sigmatrópico concertado [3,3] do intermediário alil azida.The Rh2(OAc)4 catalyzed intramolecular O-H insertion reaction of δ-hydroxy-α-diazoesters affords 3(2H)-furanone-2-carboxylates in good yield but with moderate selectivity (d.e. ca 60%). The initially formed 2,5-substituted cis-furanones were found to epimerize to the corresponding 2,5-trans isomers when subjected to silica gel chromatography. The Rh2(OAc)4 catalyzed decomposition of γ-azido-δ-hydroxy-α-diazoesters also furnished 3(2H)-furanone-2-carboxylates. These compounds are derived by a sequential O-H insertion reaction followed by a concerted [3,3]-sigmatropic shift of the allylic azide intermediate.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rhodium(II)-Catalysed Intramolecular O-H Insertion of alpha-Diazo-gamma-Azido-delta-Hydroxy-beta-Ketoesters: Evidence for a Novel Sigmatropic Rearrangement of an Allylic Azide Intermediate

Padwa¹,

Sá²

1999

J. Braz. Chem. Soc.

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“…[8][9][10] In light of recent examples of transition-metal catalysed asymmetric additions of nitrogen nucleophiles to allenes [11] and the growing utility of organic azides, we sought to develop a gold(I)-catalyzed enantioselective hydroazidation of allenes. Cognizant of potential regioselectivity issues from the Winstein rearrangement [12] of the product allylic azides, we initiated our studies using aryl allene 3a. [13] Initial studies revealed that the use of ethereal solvents was critical to obtaining reproducible data.…”

mentioning

confidence: 99%

Enantioselective, Stereodivergent Hydroazidation and Hydroamination of Allenes Catalyzed by Acyclic Diaminocarbene (ADC) Gold(I) Complexes

et al. 2016

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The gold-catalyzed enantioselective hydroazidation and hydroamination reactions of allenes are presented herein. ADC gold(I) catalysts derived from BINAM were critical for achieving high levels of enantioselectivity in both transformations. The sense of enantioinduction is reversed for the two different nucleophiles, allowing access to both enantiomers of the corresponding allylic amines using the same catalyst enantiomer. Graphical AbstractChiral allylic azides and amines may be obtained by enantioselective hydroazidation and hydroamination of allenes catalyzed by acyclic diaminocarbene gold(I) catalysts derived from BINAM. The sense of enantioinduction is reversed for the two different nucleophiles, allowing easy access to both enantiomers with a single catalyst enantiomer. Keywordshydroazidation; hydroamination; enantioselective; gold catalysis; acyclic diaminocarbene Allylic amines are an important functional motif in synthetic organic chemistry and they have been utilized in the synthesis of numerous biologically active compounds. [1] Closely related allylic azides are valuable precursors for allylic amines, as well as for amino acids [2] Correspondence to: F. Dean Toste, fdtoste@berkeley.edu. HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript and amine-containing natural products. [3] Allylic azides have typically been prepared via substitution reactions from the corresponding allylic halides, (homo)allylic alcohols, and their derivatives. [4] More recently, Pd-catalyzed C-H activation, [5] and Au-catalyzed hydroazidation of allenes [6] have been employed.While reports of the synthesis of allylic azides are numerous, methods for asymmetric azidation are few. [7] Fewer still are enantioselective hydroazidation reactions, which have only been reported in a formal sense via conjugate addition to activated double bonds (Scheme 1). [8][9][10] In light of recent examples of transition-metal catalysed asymmetric additions of nitrogen nucleophiles to allenes [11] and the growing utility of organic azides, we sought to develop a gold(I)-catalyzed enantioselective hydroazidation of allenes. Cognizant of potential regioselectivity issues from the Winstein rearrangement [12] of the product allylic azides, we initiated our studies using aryl allene 3a. [13] Initial studies revealed that the use of ethereal solvents was critical to obtaining reproducible data. [14] With the choice of solvent established, the enantioinduction afforded by a number of chiral gold(I) catalysts was evaluated under conditions similar to those previously reported, with trifluoroacetic acid (TFA) and trimethylsilyl azide (TMSN 3 ) used for in situ generation of hydrazoic acid (Table 2). [6] Traditional chiral phosphine gold(I) catalysts failed to afford high levels of enantioinduction (entries 1,2) as did a previously reported [15] phosphoramidite catalyst (entry 3). Chiral NHC gold(I) catalysts [16] (entries 4-6) also were found to be unsatisfactory. However, the use of a BINAM-derived ADC gold...

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Azido-1,2,3-triphenylpropenes of Varying Stabilities: A Corrigendum of Structure Assignment

Banert¹,

Hagedorn

Liedtke

et al. 2000

Eur. J. Org. Chem.

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A reinvestigation of the reaction between 2,3‐diphenyl‐2H‐azirine (1) and phenyldiazomethane (2) has shown that a literature report has to be corrected since no vinyl azide 4 but rather the allylic compound 3‐azido‐1,2,3‐triphenyl‐1‐propene (3) is produced. This stable substance, which can also be prepared by substitution reactions of allylic bromide (E)‐10 or from alcohol (E)‐11, may be separated into its geometrical isomers (E)‐3 and (Z)‐3, although these equilibrate through rapid [3,3] sigmatropic migration of the azido group. Attempts to synthesize 4 by dehydration of azido alcohols 7 using methanesulfonyl chloride and sulfur dioxide or by elimination of hydrogen chloride from azides 15 led only to 3 and 2‐benzyl‐2,3‐diphenyl‐2H‐azirine (14). This heterocycle, which can also be prepared by Neber rearrangement, has been found to be the thermal and photochemical decomposition product of the unstable vinyl azides 4. However, dehydrations of 7 using thionyl chloride at low temperature have led to the first isolation of 1‐azido‐1,2,3‐triphenyl‐1‐propenes (4). Starting with 3 and various other allylic azides, rearrangement reactions involving sigmatropic shift of the azido group or photochemical cis‐trans isomerization have been investigated, as have base‐catalyzed (prototropic) rearrangements to give vinyl azides.

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Rearrangement of Allylic Azides

Cited by 190 publications

References 0 publications

Rhodium(II)-Catalysed Intramolecular O-H Insertion of alpha-Diazo-gamma-Azido-delta-Hydroxy-beta-Ketoesters: Evidence for a Novel Sigmatropic Rearrangement of an Allylic Azide Intermediate

Rhodium(II)-Catalysed Intramolecular O-H Insertion of alpha-Diazo-gamma-Azido-delta-Hydroxy-beta-Ketoesters: Evidence for a Novel Sigmatropic Rearrangement of an Allylic Azide Intermediate

Enantioselective, Stereodivergent Hydroazidation and Hydroamination of Allenes Catalyzed by Acyclic Diaminocarbene (ADC) Gold(I) Complexes

Azido-1,2,3-triphenylpropenes of Varying Stabilities: A Corrigendum of Structure Assignment

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