tert-Butyloxycarbonyl and benzyloxycarbonyl amino acid fluorides. New, stable rapid-acting acylating agents for peptide synthesis

Carpino, Louis A.; Mansour, E. M. E.; Sadat-Aalaee, Dean

doi:10.1021/jo00008a005

Cited by 140 publications

(86 citation statements)

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“…38,45,46 The Z group was removed by catalytic hydrogenation in methanol (MeOH) solution. The synthesis of the mBrBz-heptapeptide 5 was achieved by use of mBrBz-OAt 38,47 (OAt, 1-oxy-7-aza-1,2,3-benzotriazole) in a 9:1 CH 2 Cl 2 /CH 3 CN solvent mixture in the presence of N-methylmorpholine.…”

Section: Figurementioning

confidence: 99%

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

et al. 2002

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As an additional step toward the dissection of the factors responsible for the onset of 3(10)-helix vs alpha-helix in peptides, in this paper we describe the results of a three-dimensional (3D) structural analysis by x-ray diffraction of the N(alpha)-acylated heptapeptide alkylamide mBrBz-L-Iva-L-(alphaMe)Val-L-Abu-L-(alphaMe)Val-L-(alphaMe)Phe-L-(alphaMe)Val-L-Iva-NHMe characterized by a single (L-Abu3) C(alpha)-trisubstituted and six C(alpha)-tetrasubstituted alpha-amino acids. We find that in the crystal state this peptide is folded in a mixed helical structure with short elements of 3(10)-helix at either terminus and a central region of alpha-helix. This finding, taken together with the published NMR and x-ray diffraction data on the all C(alpha)-methylated parent sequence and its L-Val2 analog (also the latter heptapeptide has a single C(alpha)-trisubstituted alpha-amino acid) strongly supports the view that one C(alpha)-trisubstituted alpha-amino acid inserted near the N-terminus of an N(alpha)-acylated heptapeptide alkylamide sequence may be enough to switch a regular 3(10)-helix into an essentially alpha-helical conformation. As a corollary of this work, the x-ray diffraction structure of the N(alpha)-protected, C-terminal tetrapeptide alkylamide Z-L-(alphaMe)Val-L-(alphaMe)Phe-L-(alphaMe)Val-L-Iva-NHMe, also reported here, is clearly indicative of the preference of this fully C(alpha)-methylated, short peptide for the 3(10)-helix. As the same terminally blocked sequence is mixed 3(10)/alpha-helical in the L-Abu3 heptapeptide amide but regular 3(10)-helical in the tetrapeptide amide and in the parent heptapeptide amide, these results point to an evident plasticity even of a fully C(alpha)-methylated short peptide.

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Section: Figurementioning

confidence: 99%

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

et al. 2002

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“…The formation of asymmetric diphosphanes by activation [13] or coupling [7a,c] of two alkynylphosphanes mediated by metal centers has been previously reported, but, as far as we know, the migratory insertion of an acetylenic fragment into a MÀC 6 F 5 bond has no precedent. In this context it is worth noting that a few examples of pentafluorobenzimidoyl derivatives (C(C 6 F 5 ) NR) of Ti and Pd have been obtained through insertion reactions of isocyanides into M À C 6 F 5 bonds.…”

Section: à3mentioning

confidence: 99%

Double Insertion of Coordinated Phosphanylalkyne Ligands into a Pt−C6F5 Bond

Charmant

Forniés

Gómez

et al. 1999

Angew. Chem. Int. Ed.

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Enhanced reactivity is shown by uncoordinated C identical withC bonds in the proximity of a metal in phosphanylacetylene complexes. cis-[Pt(C(6)F(5))(2)(thf)(2)] reacts with [M(C(6)F(5))(2)(PPh(2)C identical withCPh)(2)] (M=Pt, Pd) to form binuclear complexes containing the novel 2,3-bis(diphenylphosphanyl)-1,3-butadien-1-yl bridging ligand. Substitution of the solvent ligands with, for example, PPh(2)H (see picture) provides species that could be characterized by X-ray crystallography.

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“…For instance, N-alkylation of 8 with benzyl bromoacetate gave, after hydrogenolytic cleavage of the benzyl ester group, the Boc-Phe-Gly dipeptide analogue 9 (Scheme 2). Coupling of 9 with a-amino isobutyric acid [ benzyl ester (AibOBn) according to the procedure of Carpino et al [13] and subsequent O-debenzylation provided the tripeptide 10 (m.p. 183 ± 185 8C, [a] 25 D 89.7 (CH 2 Cl 2 , c 0.24)).…”

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confidence: 99%

α-Alkyl-α-Amino-β-Lactam Peptides: Design, Synthesis, and Conformational Features

Palomo¹,

Aizpurua²,

Benito³

et al. 1999

Angew. Chem. Int. Ed.

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tert-Butyloxycarbonyl and benzyloxycarbonyl amino acid fluorides. New, stable rapid-acting acylating agents for peptide synthesis

Cited by 140 publications

References 1 publication

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

Double Insertion of Coordinated Phosphanylalkyne Ligands into a Pt−C6F5 Bond

α-Alkyl-α-Amino-β-Lactam Peptides: Design, Synthesis, and Conformational Features

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tert-Butyloxycarbonyl and benzyloxycarbonyl amino acid fluorides. New, stable rapid-acting acylating agents for peptide synthesis

Cited by 140 publications

References 1 publication

Factors governing 310‐helix vs α‐helix formation in peptides: Percentage of Cα‐tetrasubstituted α‐amino acid residues and sequence dependence

Factors governing 310‐helix vs α‐helix formation in peptides: Percentage of Cα‐tetrasubstituted α‐amino acid residues and sequence dependence

Double Insertion of Coordinated Phosphanylalkyne Ligands into a Pt−C6F5 Bond

α-Alkyl-α-Amino-β-Lactam Peptides: Design, Synthesis, and Conformational Features

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Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence