2004
DOI: 10.1002/ejic.200400504
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Rearrangement of the Active Ester Intermediate During HOBt/EDC Amide Coupling

Abstract: Keywords: Ferrocene / Hydroxybenzotriazole / Amide coupling / Amino acid / Electrochemistry 3-{[1Ј-(tert-Butyloxycarbonylamino)ferrocen-1-yl]carbonyl}-benzotriazole 1-oxide (3) has been successfully separated during the synthesis of benzotriazol-1-yl 1Ј-(tert-butyloxycarbonylamino)ferrocene-1-carboxylate (2) as an active ester for peptide coupling. The yield of 3 increased by using polar, rather than nonpolar solvents. The two compounds have been fully characterized and studied by X-ray crystallography and spe… Show more

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Cited by 29 publications
(15 citation statements)
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“…[18][19][20][21][22][23] This unit has been successfully used for the activation of carbonyl functionalized ferrocenes for the formation of amino acid conjugates. [22,24] HOBt has been used occasionally to activate sulfonic acid derivatives [25,26] and we hypothesized that a similarly structured sulfonyl group would allow for the rapid generation of ferrocene bis(sulfonamides). Thus, we prepared compound 4, 1,1'-bis(sulfonyl-N-hydroxybenzotriazole)ferrocene, which is produced from the reaction of compound 1 with 1-hydroxybenzotriazole hydrate.…”
Section: Resultsmentioning
confidence: 99%
“…[18][19][20][21][22][23] This unit has been successfully used for the activation of carbonyl functionalized ferrocenes for the formation of amino acid conjugates. [22,24] HOBt has been used occasionally to activate sulfonic acid derivatives [25,26] and we hypothesized that a similarly structured sulfonyl group would allow for the rapid generation of ferrocene bis(sulfonamides). Thus, we prepared compound 4, 1,1'-bis(sulfonyl-N-hydroxybenzotriazole)ferrocene, which is produced from the reaction of compound 1 with 1-hydroxybenzotriazole hydrate.…”
Section: Resultsmentioning
confidence: 99%
“…The two ester groups are in the 1,2′ conformation around the ferrocene center, they are almost coplanar to the Cp rings with torsion angles for C(14)-C10)-C(15)-O(12) and C(24)-C(20)-C(25)-O(22) of 1.1 (3)° and -0.3 (3)°, respectively, unlike to those found in Fc-C(O)-OBt (10.06 (10)°; Kraatz et al, 1997) and Boc-N(H)-Fc-C(O)-OBt (5.0 (7)°; Mahmoud et al, 2005). The benzotriazole moiety is perpendicular with respect to the Cp it is attached to [C(15) -O(12)-N(11)-C(16)] = 87.0 (0)°).…”
Section: S1 Commentmentioning
confidence: 72%
“…For related literature, see: Heinze & Schlenker (2004); Kraatz et al (1997); Mahmoud et al (2005); Taylor & Kennard (1982).…”
Section: Related Literaturementioning
confidence: 99%
See 1 more Smart Citation
“…14, 19 The Boc-protected dipeptide promoieties ( 12 ) were prepared using a standard EDC coupling method. 26 Conjugates 4 and 5 were synthesized as outlined in Scheme 2. The Boc-protected intermediate 13 was prepared by treatment of 10 or 11 with the N -Boc-protected dipeptide promoiety ( 12 ) using PyBOP and DIPEA in DMF at 40 ºC.…”
mentioning
confidence: 99%