Total Synthesis of Thiangazole

Ehrler, Juerg; Farooq, Saleem

doi:10.1055/s-1994-22977

Cited by 36 publications

(18 citation statements)

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“…With NaH as a base, 6 vinylthiazoline 5a was produced in very low yield (18%). However, using DBU/LiCl in acetonitrile as the deprotonation agent, 7 various aldehydes and acetone could be successfully coupled. The reaction was then performed with the chiral thiazoline phosphonates 4b and 4e (Scheme 3).…”

Section: Methodsmentioning

confidence: 99%

“…For example, L-084 (1-b-methylcarbapenem carrying thiazoline ring) is a new oral antibiotic, 5 arylvinyl thiazolines are antihelmintic and antifungal agents 6 and thiangazole alkaloid is the subject of particular attention because of its high potency in HIV inhibition. 4,7 Used several years ago as an aldehyde source by A. I. Meyers, 8 thiazolines continued to find applications as synthetic intermediates. 9 As well as phosphonylated oxazolines I, 10 sulfur analogues II are convenient Horner-Wadsworth-Emmons (H. W. E.) reagents for the introduction of a thiazoline ring into an organic structure.…”

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confidence: 99%

“…9 As well as phosphonylated oxazolines I, 10 sulfur analogues II are convenient Horner-Wadsworth-Emmons (H. W. E.) reagents for the introduction of a thiazoline ring into an organic structure. 6,7 Nevertheless, to the best of our knowledge, only two methods have been described for the synthesis of these thiazolines. The first starts from cyanomethyl phosphonate and either a b-aminoethanethiol 6 or a cysteine derivative.…”

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confidence: 99%

“…The first starts from cyanomethyl phosphonate and either a b-aminoethanethiol 6 or a cysteine derivative. 7 The second, developed in our laboratory, employed phosphonodithioacetate and bromoethyl amine hydrochloride. 11 However, these syntheses cannot be easily generalised because of the limited availability of the starting materials (b-amino thiols or bromides).…”

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Synthesis of New Asymmetric Phosphonylated Thiazolines and their Use in Olefination Reactions

et al. 2000

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N-(2-Hydroxyalkyl)-2-phosphonoethanethioamides were prepared from a readily accessible phosphonodithioacetate and commercial chiral b-amino alcohols. Taking advantage of both the presence of the hydroxy group (nucleofuge) and of the C=S (nucleophile) in the same molecule, we obtained new chiral phosphonylated thiazolines by an intramolecular cyclisation using the Mitsunobu procedure. These thiazoline-phosphonates were then involved in Horner-Wadsworth-Emmons reaction to give asymmetric vinylic thiazolines.Although less studied than oxazolines, 1 their sulfur analogues, thiazolines, have recently seen an increasing interest due to the presence of this heterocycle in the structure of many biologically active compounds including natural products (such as anguibactin, 2 curacin A, 3 tantazoles and mirabazoles 4 ). For example, L-084 (1-b-methylcarbapenem carrying thiazoline ring) is a new oral antibiotic, 5 arylvinyl thiazolines are antihelmintic and antifungal agents 6 and thiangazole alkaloid is the subject of particular attention because of its high potency in HIV inhibition. 4,7 Used several years ago as an aldehyde source by A. I. Meyers, 8 thiazolines continued to find applications as synthetic intermediates. 9 As well as phosphonylated oxazolines I, 10 sulfur analogues II are convenient HornerWadsworth-Emmons (H. W. E.) reagents for the introduction of a thiazoline ring into an organic structure. 6,7 Nevertheless, to the best of our knowledge, only two methods have been described for the synthesis of these thiazolines. The first starts from cyanomethyl phosphonate and either a b-aminoethanethiol 6 or a cysteine derivative. 7 The second, developed in our laboratory, employed phosphonodithioacetate and bromoethyl amine hydrochloride. 11 However, these syntheses cannot be easily generalised because of the limited availability of the starting materials (b-amino thiols or bromides). Therefore, efficient routes are still needed for the preparation of new phosphonylated thiazoline (especially with chiral thiazoline moiety).This report describes a facile synthesis of chiral phosphonylated thiazolines starting from readily accessible ethyl phosphonodithioacetate 12 and commercial b-amino alcohols. The Mitsunobu procedure 13,14 was used to perform the internal cyclisation of intermediate hydroxy substituted thioamides. Some of the resulting phosphonylated thiazolines were then involved in the H◊W◊E reaction for the synthesis of new vinylic chiral thiazolines.N-(2-Hydroxyalkyl)-2-phosphonoethanethioamides 3a-e were readily prepared by amination 12,15 of the phosphonodithioacetate 1 with achiral or enantiopure amino alcohols 2a-e (Scheme 1). Phosphonylated thioamides 3a-e were thus obtained in good yields after purification (Table 1). Scheme 1The resulting thioamides 3a-e were then treated with 1.5 equivalents of PPh 3 /DEAD in toluene (Scheme 2). After 48 hours at room temperature, the reaction was complete Table 1 Product R Amino alcohol 31 P NMR (CDCl 3 ), d (ppm) Isolated Yield (%) [a] 20 D (c, CHCl 3 ) 3a H ethanola...

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Section: Methodsmentioning

confidence: 99%

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Synthesis of New Asymmetric Phosphonylated Thiazolines and their Use in Olefination Reactions

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“…However, these highly nucleophilic conditions are not fully compatible with the labile nature of a sulfhydryl group and afforded the target alkylation products in rather moderate (≈ 50 %) chemical yields. Among other literature approaches reported for preparation of α‐(methyl)cysteine 1 is the resolution of the corresponding racemic derivatives by using bio‐catalysis and HPLC on chiral stationary phases …”

Section: Introductionmentioning

confidence: 99%

Operationally Convenient and Scalable Asymmetric Synthesis of (2S)‐ and (2R)‐α‐(Methyl)cysteine Derivatives through Alkylation of Chiral Alanine Schiff Base Ni^II Complexes

et al. 2017

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This research demonstrates that the methylation of N‐benzyl cysteine Schiff base derived NiII complexes leads to the formation of the corresponding dehydroalanine‐containing products and cannot be used for preparation of the target α‐(methyl)cysteine. In sharp contrast, the alternative strategy that involves thiomethylation of NiII complexes of alanine Schiff bases is a viable and practically attractive approach to afford the desired α‐(methyl)cysteine containing derivatives. This work also reveals a significant, and rather unexpected, difference in the stereochemical performance of proline and 3,5‐dihydro‐4H‐dinaphth[2,1‐c:1′,2′‐e]azepine derived chiral ligands, the former of which shows superior performance in terms of chemical yields and diastereoselectivity of the α‐(methyl)cysteine products formed.

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Natural products as pesticides: Two examples of stereoselective synthesis

et al. 1996

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Total Synthesis of Thiangazole

Cited by 36 publications

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Synthesis of New Asymmetric Phosphonylated Thiazolines and their Use in Olefination Reactions

Synthesis of New Asymmetric Phosphonylated Thiazolines and their Use in Olefination Reactions

Operationally Convenient and Scalable Asymmetric Synthesis of (2S)‐ and (2R)‐α‐(Methyl)cysteine Derivatives through Alkylation of Chiral Alanine Schiff Base Ni^II Complexes

Natural products as pesticides: Two examples of stereoselective synthesis

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Total Synthesis of Thiangazole

Cited by 36 publications

References 0 publications

Synthesis of New Asymmetric Phosphonylated Thiazolines and their Use in Olefination Reactions

Synthesis of New Asymmetric Phosphonylated Thiazolines and their Use in Olefination Reactions

Operationally Convenient and Scalable Asymmetric Synthesis of (2S)‐ and (2R)‐α‐(Methyl)cysteine Derivatives through Alkylation of Chiral Alanine Schiff Base NiII Complexes

Natural products as pesticides: Two examples of stereoselective synthesis

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Operationally Convenient and Scalable Asymmetric Synthesis of (2S)‐ and (2R)‐α‐(Methyl)cysteine Derivatives through Alkylation of Chiral Alanine Schiff Base Ni^II Complexes