Fast and efficient preparation of Baylis–Hillman-derived (E)-allylic azides and related compounds in aqueous medium

Sá, Marcus M.; Ramos, Marcia D.; Fernandes, Luciano

doi:10.1016/j.tet.2006.09.059

Cited by 57 publications

(16 citation statements)

References 43 publications

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“…The anticipated Z-stereochemistry assigned to all allylic bromides 1 was based on the characteristic NMR shift of the highly deshielded β-olefinic hydrogen cis to the carboxyl group 15,18,[22][23][24] and also on the previous X-ray crystallography analysis of 1e. 33 Products were obtained nearly pure and no signals for an elusive formation of E-isomer was ever detected.…”

Section: Resultsmentioning

confidence: 99%

“…Compounds 1a,b,e,f,g,i,k,l showed physical and spectral data in accordance with their expected structure and by comparison with data in literature. 8,11,18,[20][21][22][23][24][25] Methyl (Z)-2-(bromomethyl)-3-(4-methoxyphenyl) …”

Section: Methyl 3-hydroxy-2-methylene-3-(2-chlorophenyl) Propanoate (2g)mentioning

confidence: 99%

“…18 In spite of the fairly good yields often achieved for this transformation, the required use of large quantities of noxious hydrobromic acid is a major disadvantage due to safety and environmental concerns. Alternative methods for converting alcohol 2 to bromide 1 include the use of NBS/Me 2 20 and also bromine salts immobilized in ionic liquids 21 or in the presence of solid catalysts such as montmorillonite KSF clay, 22 Amberlyst-15, 23 silica gel-supported NaHSO 4 , 24 and silica gel alone under microwave irradiation. 25 Although all the above procedures have their own applications, many of them suffer from one or more drawbacks such as the use of harmful conditions, high temperatures, special equipment or commercially unavailable reagents or catalysts, eventually leading to long reaction times or low yields.…”

Section: Introductionmentioning

confidence: 99%

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A highly efficient and general method for the preparation of (Z)-allylic bromides derived from Morita-Baylis-Hillman adducts

Ferreira¹,

Fernandes²,

Sá³

2009

J. Braz. Chem. Soc.

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(Z)-2-(Bromometil)-2-alcenoatos são importantes intermediários sintéticos e foram preparados de forma simples e prática pelo tratamento de α-metileno-β-hidroxiésteres (produtos da reação de Morita-Baylis-Hillman) com LiBr/H 2 SO 4 em acetonitrila à temperatura ambiente. Além de fornecer altos rendimentos e de tolerar a presença de diversos grupos funcionais, esta nova metodologia utiliza reagentes baratos e não faz uso de HBr.Representative (Z)-2-(bromomethyl)-2-alkenoates were easily prepared in high yield by treating α-methylene-β-hydroxyesters (Morita-Baylis-Hillman adducts) with LiBr/H 2 SO 4 in acetonitrile at room temperature. Besides the tolerance to many diverse functional groups, this new methodology employs inexpensive reagents and avoids the use of HBr.

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Section: Resultsmentioning

confidence: 99%

Section: Methyl 3-hydroxy-2-methylene-3-(2-chlorophenyl) Propanoate (2g)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A highly efficient and general method for the preparation of (Z)-allylic bromides derived from Morita-Baylis-Hillman adducts

Ferreira¹,

Fernandes²,

Sá³

2009

J. Braz. Chem. Soc.

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“…Propargyl phenyl ether (1) [20] and ethyl 2-azidoacetate (2) [21] were used as representative substrates in this screening (Scheme 1). All the reactions were carried out in water under continuous sonication for 120 min.…”

Section: Resultsmentioning

confidence: 99%

“…Substituted terminal alkynes were synthesized according to the literature [20, 23 -26]. Benzyl azide [21] and phenyl azide [27] were also synthesized according to previous reports.…”

Section: Generalmentioning

confidence: 99%

An Efficient Ultrasound-assisted Method for the Synthesis of 1,4-Disubstituted Triazoles

Jiang

Chen

et al. 2011

Zeitschrift Für Naturforschung B

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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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Fast and efficient preparation of Baylis–Hillman-derived (E)-allylic azides and related compounds in aqueous medium

Cited by 57 publications

References 43 publications

A highly efficient and general method for the preparation of (Z)-allylic bromides derived from Morita-Baylis-Hillman adducts

A highly efficient and general method for the preparation of (Z)-allylic bromides derived from Morita-Baylis-Hillman adducts

An Efficient Ultrasound-assisted Method for the Synthesis of 1,4-Disubstituted Triazoles

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

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