150650-46-7Relevant academic research and scientific papers
Studies related to the carbohydrate sectors of esperamicin and calicheamicin: Definition of the stability limits of the esperamicin domain and fashioning of a glycosyl donor from the calicheamicin domain
Halcomb, Randall L.,Boyer, Serge H.,Wittman, Mark D.,Olson, Steven H.,Denhart, Derek J.,Liu, Kevin K. C.,Danishefsky, Samuel J.
, p. 5720 - 5749 (2007/10/02)
The core trisaccharide regions of esperamicin and the aryltetrasaccharide region of calicheamicin have been synthesized. The minimum protection modalities necessary to stabilize structures against rearrangement to an isomeric azafuranose series were ascertained (see compounds 12 and 65). Deprotection of the 2-(trimethylsilyl)-ethoxycarbonyl carbamate from 65 led to azafuranose 14 characterized as methyl glycoside 15. Using this insight, it was possible to fashion, for the first time, a pre-glycosyl donor (see compound 128) corresponding to the complete arylsaccharide sector of calicheamicin γ1I at the oxidation level of the domain. Among the key assembly strategies were the conversion of α-thiophenylpseudoglycals to allal derivatives (see 44 → 45); the interfacing of epoxide-mediated glycosylation with iodoglycosylation (see 30 → 47 → 48); the synthesis of hydroxylamine glycosides via inflate displacement (see 61 + 91 → 101); and a new route to p-hydroxybenzonitriles (see formation of 86).
Reductive Desilanolation as a Route to Benzonitriles. An Application to a Concise Synthesis of the Aromatic Sector of Calicheamicin.
Olson, Steven H.,Danishefsky, Samuel J.
, p. 7901 - 7904 (2007/10/02)
The TMS-cyanohydrins of quinones undergo reductive desilanolation in the presence of samarium iodide to form hydroxybenzonitriles.Benzoquinone 1 was converted to the hexasubstituted aromatic fragment of calicheamicin 4 by this method.
Total synthesis of calicheamicin γ1I. 1. Synthesis of the oligosaccharide fragment
Groneberg,Miyazaki,Stylianides,Schulze,Stahl,Schreiner,Suzuki,Iwabuchi,Smith,Nicolaou
, p. 7593 - 7611 (2007/10/02)
The first total synthesis of the calicheamicin γ1I oligosaccharide fragment in the form of its methyl glycoside (62) has been achieved. The synthetic challenge of the B-ring was recognized and studied initially, resulting in a novel and unique solution to the stereochemical problems posed involving a [3,3]-sigmatropic rearrangement of an allylic thionoimidazolide (111). This chemistry was initially worked out on a model for the ABC-ring system (47) and then successfully applied to the real system. The success of this synthesis has enabled the completion of the first synthesis of the natural product itself, calicheamicin γ1I (1), as will be described in the following papers in this issue.
A new process for the regiocontrolled synthesis of substituted catechols and other 1,2-dioxygenated aromatics: Conjugate addition of vinyl-, aryl-, and heteroarylcopper reagents to cyclobutenediones followed by thermal rearrangement
Gurski, Angela,Liebeskind, Lanny S.
, p. 6101 - 6108 (2007/10/02)
A general method for the synthesis of substituted catechol derivatives has been developed utilizing the 1,4-addition of vinyl-, aryl-, and heteroarylcuprates to cyclobutenediones followed by thermal rearrangement. In situ protection with (methoxyethoxy)methyl chloride of the enolate derived from addition of the cuprate yields 2-alkoxy-4-Runsat'd-2-cyclobutenones, which rearrange thermally to substituted catechols with differentiated hydroxy groups. Monosubstituted cyclobutenediones undergo highly regioselective 1,4-addition at the unsubstituted carbon; alternatively, regiocontrol can be exerted by addition to cyclobutenedione monoacetals. Differentially disubstituted cyclobutenedione monoacetals undergo regiospecific 1,4-addition to the unprotected enone moiety. Protection of the intermediate enolate and mild hydrolysis of the acetal yield 3,4-disubstituted 2-alkoxy-4-RUnsat'd-2-cyclobutenones regiospecifically. Thermolysis of these products delivers substituted catechol monoethers regiospecifically.
