X=y-ZH compounds as potential 1,3-dipoles. part 44.1 asymmetric 1,3-dipolar cycloaddition reactions of imines and chiral cyclic dipolarophiles

Cooper, David; Grigg, Ronald; Hargreaves, S.; Kennewell, P. D.; Redpath, James

doi:10.1016/0040-4020(95)00397-q

Cited by 64 publications

(30 citation statements)

References 13 publications

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“…In both cases, the IR, NMR, and MS data were identical with those of rac-1 [65]. The optical rotation in CHCl 3 was [a] 22 D 106.4 for (R)-1 and À 120.6 for the (S)-1 isomer. A solution of equimolar amounts (0.8 mmol) of (R)-1 and (S)-1, respectively, and imine 2 in HMPA was slowly dropped into a solution of 0.2 mmol trimethylsilyl triflate and 0.2 mmol of CsF in HMPA.…”

Section: Resultssupporting

confidence: 49%

Synthesis of an Enantiomerically Pure 1,3-Thiazole-5(4H)-thione and Its Stereoselective 1,3-Dipolar Cycloaddition with an Azomethine Ylide

Gebert¹,

Heimgartner²

2002

HCA

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Starting from the enantiomerically pure 2H-azirin-3-amines (R,S)-4 and (S,S)-4, the enantiomeric, optically active 4-benzyl-4-methyl-2-phenyl-1,3-thiazole-5(4H)-thiones (R)-1 and (S)-1, respectively, have been prepared (Schemes 2 and 3). In each case, the reaction of 1 with N-(benzylidene)[(trimethylsilyl)methyl]amine (2) in HMPA in the presence of CsF and trimethylsilyl triflate gave a mixture of four optically active spirocyclic cycloadducts (Scheme 4). Separation by preparative HPLC yielded two pure diastereoisomers, e.g., (4R,5R,9S)-10 and (4R,5R,9R)-10. The regioisomeric compounds 11 were obtained as a mixture of diastereoisomers. The products were formed by a 1,3-dipolar cycloaddition of 1 with in situ generated azomethine ylide 3, which attacks 1 stereoselectively from the sterically less-hindered side, i.e., with (R)-1 the attack occurs from the reside and in the case of (S)-1 from the si-side.1. Introduction. ± Since the first [2 3] cycloadditions, described by Huisgen and coworkers [1 ± 5], azomethine ylides became a well-known class of 1,3-dipoles, and they found many applications in the synthesis of five-membered heterocycles [6 ± 17]. The 1,3-cycloaddition with olefins and acetylenes has frequently been used for the preparation of pyrrolidines and pyrroles with a large range of substitution [3] [7] [18 ± 24], and DeShong et al. described an intramolecular variation for the synthesis of bicyclic pyrrolidines and pyrroles [25]. Azomethine ylides were also used in the synthesis of indolizines [26] and other natural products [12] [27 ± 29], recent examples being those of epibatidine and epiboxidine, which were found to have potential analgesic activity [30] [31]. On the other hand, analogous reactions with thiocarbonyl compounds leading to 1,3-thiazolidines are rarely described [32 ± 37], but recently, Gallagher and co-workers published an elegant synthesis of penam and penem skeletons by 1,3-dipolar cycloadditions of azomethine ylides with thioketones [38]. Convenient methods to generate nonstabilized azomethine ylides are the desilylation of a-silyliminium salts [11] [12] [39] [40] and a-cyano-a'-silylamines, [32] or the treatment of a-silylated imines with trimethylsilyl triflate [41] (for other methods see [42 ± 50]).For many years, our research interest has been focused on the reactivity of the thiocarbonyl group in 1,3-dipolar cycloaddition reactions [51 ± 56]. In the last few years, we reported on the cycloadditions of azomethine ylides with aromatic thioketones [57] [58] and 1,3-thiazole-5(4H)-thiones [59] [60]. Recently, we reported on a stereoselective cycloaddition of an azomethine ylide, generated via thermal ring opening of cis-1-methyl-2,3-diphenylaziridine, with a chiral 1,3-thiazole-5(4H)-thione [61].

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Section: Resultssupporting

confidence: 49%

Synthesis of an Enantiomerically Pure 1,3-Thiazole-5(4H)-thione and Its Stereoselective 1,3-Dipolar Cycloaddition with an Azomethine Ylide

Gebert¹,

Heimgartner²

2002

HCA

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“…Once again the process proceeds via an endo transition state and as expected the lithio azomethine ylide adds to the face of the dipolarophile 11 trans to the O-menthyl group. 18 Hence, the newly created stereocentres are 1S, 2R, 4S, and 5R (Scheme 4).…”

Section: Metal Ion Catalysed Cycloadditionmentioning

confidence: 99%

X=Y=ZH Systems as potential 1,3-dipoles. Part 58: Cycloaddition route to chiral conformationally constrained (R)-pro-(S)-pro peptidomimetics

2003

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“…192,194,195 However, excellent results have also been achieved with chiral acrylamides, and the synthesis of a number of biologically active compounds has been accomplished through their use.…”

Section: Asymmetric 13-dipolar Cycloadditions Of Azomethine Ylidesmentioning

confidence: 99%

Asymmetric 1,3-dipolar cycloadditions of acrylamides

2010

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This critical review, which is relevant to researchers in synthetic organic chemistry, focuses on asymmetric 1,3-dipolar cycloadditions with acrylamides. The use of chiral acrylamides as dipolarophiles leads to high levels of stereocontrol, due to conformational constraint in the acrylamides. Employment of chiral tertiary acrylamides containing nitrogen heterocycles is particularly effective in controlling the stereoselectivity. Following a general overview of 1,3-dipolar cycloadditions, the main body of the review focuses on asymmetric 1,3-dipolar cycloadditions of acrylamides with nitrile oxides, nitrones, diazoalkanes and azomethine ylides, with particular emphasis on the rationale for the observed stereocontrol (215 references)

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X=y-ZH compounds as potential 1,3-dipoles. part 44.1 asymmetric 1,3-dipolar cycloaddition reactions of imines and chiral cyclic dipolarophiles

Cited by 64 publications

References 13 publications

Synthesis of an Enantiomerically Pure 1,3-Thiazole-5(4H)-thione and Its Stereoselective 1,3-Dipolar Cycloaddition with an Azomethine Ylide

Synthesis of an Enantiomerically Pure 1,3-Thiazole-5(4H)-thione and Its Stereoselective 1,3-Dipolar Cycloaddition with an Azomethine Ylide

X=Y=ZH Systems as potential 1,3-dipoles. Part 58: Cycloaddition route to chiral conformationally constrained (R)-pro-(S)-pro peptidomimetics

Asymmetric 1,3-dipolar cycloadditions of acrylamides

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