Synthesis of (2S,3S)-3′-fluoroisoleucine

Charrier, Jean-Damien; Hadfield, David S.; Hitchcock, Peter B.; Young, Douglas W.

doi:10.1039/b316219b

Cited by 15 publications

(14 citation statements)

References 10 publications

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“…On the one hand first-principle calculations can help in understanding the equilibrium solid-liquid structure. Such calculations have recently been performed for KDP 7 and were found to be in promising agreement with the experimental results. The other approach is through Molecular Dynamics simulations using effective potentials to describe the interactions between the various components in the growth system.…”

Section: Closing the Gap?supporting

confidence: 65%

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Towards an atomic-scale understanding of crystal growth in solution

et al. 2007

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Section: Closing the Gap?supporting

confidence: 65%

“…density-functional theory and such results are starting to appear only now. 7 All in all it can be stated that computer modelling is slowly gaining territory in the complexity direction, but only on small systems and with several parameters from real systems still left out.…”

Section: Introductionmentioning

confidence: 99%

Towards an atomic-scale understanding of crystal growth in solution

et al. 2007

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“…To gain further evidence for this assignment, the 13 C-1 H coupling constants from a 1 H-coupled 13 C NMR experiment were examined. Typically a proton cis to a carbonyl group in an a,b-unsaturated ester will have a much smaller coupling (4)(5)(6)(7)(8)(9)(10) to the carbonyl carbon than a proton trans (10)(11)(12)(13)(14)(15)(16)(17)(18). 7 Despite this being a welldocumented coupling, measurements of this type have rarely been used to assign the geometry in acrylate derivatives.…”

Section: Papermentioning

confidence: 99%

“…The combined organic layers were dried (MgSO 4 ), filtered, and concentrated in vacuo to give the title compound (2.7 g, 85%) as a white solid; mp 73-74 °C [Lit. 16 [a] D 23 -24.0 (c 2.0, MeOH) [Lit. MeOH)].…”

Section: (2s4r)-2-(tert-butoxycarbonylamino)-4-methylpentan-15-dioimentioning

confidence: 99%

Stereochemical Assignments of the Chlorinated Residues in Victorin C

Durow¹,

Willis²

2009

Synthesis

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Victorins are cyclic pentapeptide natural products isolated from the fungus Cochliobus victoriae. Using a combination of synthesis and spectroscopic methods we have assigned the geometry of the vinyl chloride residue and determined the stereochemistry of the 5,5-dichloroleucine moiety.Victoria blight is a disease of oats caused by the fungus Cochliobolus victoriae (also known as Helminthosporium victoriae) which only affects oat crops that have been derived from the oat variety Victoria. Five fractions displaying host-selective activity were isolated from the culture filtrate of C. victoriae and collectively these are known as 'victorin', 'the victorins' or HV-toxins. 1 Approximately 1-2 mg of the major metabolite, victorin C 2, was isolated from 1 L of culture broth and the NMR spectrum was complicated by the presence of different conformers. 1a,bThe cyclic pentapeptide structures of the victorins 1-5 ( Figure 1) were elucidated by extensive spectroscopic studies combined with degradation of the natural products. 1,2 The L-configuration of each amino acid residue was determined from the ORD shifts of their 2,4-DNP derivatives. 2 In addition the stereochemistry of erythro-bhydroxyleucine and threo-b-hydroxylysine residues were assigned by correlation with synthetic materials. 1,2 However, the unequivocal assignment of the stereochemistry of the two chlorinated moieties, 5,5-dichloroleucine and the a-amino-b-chloroacrylic acid requires further investigation. Herein we describe our synthetic and spectroscopic studies leading to elucidation of the geometry of the vinyl chloride moiety and stereochemistry of 5,5-dichloroleucine. Assignment of the Geometry of the a-Amino-b-chloroacrylic Acid ResidueThe 1 H NMR spectrum of the major metabolite from cultures of C. victoriae, victorin C (2) displayed a signal at d = 7.52, which was attributed to the vinylic proton, but the geometry of the vinyl chloride (highlighted in Figure 1) was not assigned by Macko, Arigoni and coworkers. 1a-c Subsequently Kinoshita, Daly, and co-workers isolated a further metabolite, victorin M (or HV-toxin M) (5), which differs from the other victorins in that the glyoxylic acid portion (R 3 , Figure 1) is replaced by glycine. 2 Following acetylation of victorin M (5) and methylation with diazomethane, they isolated methyl ester 6 as the major product as well as traces of methyl enol ethers 7 and 8, formed by displacement of the vinyl chloride (Scheme 1).Kinoshita, Daly, and co-workers 2 suggested that the geometry of the vinyl chloride in victorin M (5) was Z by comparison of the chemical shift (d = 7.68) of the olefinic proton in derivative 6 to that of (E) and (Z)-chloroacrylic acids 9 and 10 ( Figure 2). In the E-isomer 9, the b-proton is cis to the carboxylic acid and resonates at d = 7.32, similar to that observed for the signal assigned to the vinyl chloride in 6, whereas in the Z-isomer 10 the signal is upfield at d = 6.85. However, this assignment does not take into account the effect of the nitrogen of the peptide bond on the chemical s...

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“…It was shown that irradiation of L-isoleucine in either trifluoroacetic acid (TFA) or 50% sulfuric acid in the presence of chlorine gave the L-5-chloroisoleucine which was not purified but treated directly with base to give a concise synthesis of trans-L-3-methylproline in 33% yield [32]. Whilst this chapter is focused on the synthesis of bromo-, chloro-, and iodo-a-amino acids, it is pertinent to note that in 2004 Young et al reported the stereoselective synthesis of (2S,3S)-3 0 -fluoroisoleucine from (S)-pyroglutamic acid for incorporation into ubiquitin to study protein interactions ( [33] and references cited therein).…”

mentioning

confidence: 99%