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Frank Seela - One of the best experts on this subject based on the ideXlab platform.
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glycosylation of pyrrolo 2 3 d pyrimidines with 1 o acetyl 2 3 5 tri o benzoyl β d Ribofuranose substituents and protecting groups effecting the synthesis of 7 deazapurine ribonucleosides
Journal of Organic Chemistry, 2018Co-Authors: Sachin A Ingale, Peter Leonard, Frank SeelaAbstract:Glycosylation of nonfunctionalized 6-chloro-7-deazapurine with commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-Ribofuranose (45%) followed by amination and deprotection gave tubercidin in only two steps. Similar conditions applied for the synthesis of 7-deazaguanosine employing pivaloylated 2-amino-6-chloro-7-deazapurine gave 18% glycosylation yield. The less bulky isobutyryl or acetyl protected amino group directed the glycosylation toward the exocyclic amino substituent. 7-Halogenated intermediates were glycosylated followed by dehalogenation to overcome the low glycosylation yield in the synthesis of 7-deazaguanosine.
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Glycosylation of Pyrrolo[2,3‑d]pyrimidines with 1‑O‑Acetyl-2,3,5-tri‑O‑benzoyl-β‑d‑Ribofuranose: Substituents and Protecting Groups Effecting the Synthesis of 7‑Deazapurine Ribonucleosides
2018Co-Authors: Sachin A Ingale, Peter Leonard, Frank SeelaAbstract:Glycosylation of nonfunctionalized 6-chloro-7-deazapurine with commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-Ribofuranose (45%) followed by amination and deprotection gave tubercidin in only two steps. Similar conditions applied for the synthesis of 7-deazaguanosine employing pivaloylated 2-amino-6-chloro-7-deazapurine gave 18% glycosylation yield. The less bulky isobutyryl or acetyl protected amino group directed the glycosylation toward the exocyclic amino substituent. 7-Halogenated intermediates were glycosylated followed by dehalogenation to overcome the low glycosylation yield in the synthesis of 7-deazaguanosine
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studies on the glycosylation of pyrrolo 2 3 d pyrimidines with 1 o acetyl 2 3 5 tri o benzoyl beta d Ribofuranose the formation of regioisomers during toyocamycin and 7 deazainosine syntheses
Nucleosides Nucleotides & Nucleic Acids, 2009Co-Authors: Peter Leonard, Sachin A Ingale, Ping Ding, Xin Ming, Frank SeelaAbstract:Glycosylation of silylated 4-amino-6-bromo-5-cyano-7H-pyrrolo[2,3-d]pyrimidine (9) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-Ribofuranose (10) under “one-pot” glycosylation conditions (MeCN, TMSOTf) yielded the N-7 isomer 11 together with the N-1 compound 13 (ratio = 2:1). When the same conditions were applied to 4-hydroxy-7H-pyrrolo[2,3-d]pyrimidine (21) the N-3 isomer 22 was the only glycosylation product formed in almost quantitative yield.
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an efficient synthesis of 7 functionalized 7 deazapurine beta d or beta l ribonucleosides glycosylation of pyrrolo 2 3 d pyrimidines with 1 o acetyl 2 3 5 tri o benzoyl d or l Ribofuranose
Nucleosides Nucleotides & Nucleic Acids, 2007Co-Authors: Xiaohua Peng, Frank SeelaAbstract:The glycosylation reaction performed with 7-halogenated 7-deazapurines employing commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-D- or L-Ribofuranoses is described.
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7 functionalized 7 deazapurine β d and β l ribonucleosides related to tubercidin and 7 deazainosine glycosylation of pyrrolo 2 3 d pyrimidines with 1 o acetyl 2 3 5 tri o benzoyl β d or β l Ribofuranose
Tetrahedron, 2007Co-Authors: Frank Seela, Xin MingAbstract:Abstract Several 7-functionalized 7-deazapurine ribonucleosides were prepared. Glycosylation of 7-halogenated 6-chloro-7-deazapurines with 1-O-acetyl-2,3,5-tri-O-benzoyl-β- d -Ribofuranose or 1-O-acetyl-2,3,5-tri-O-benzoyl-β- l -Ribofuranose gave the protected β- d -nucleosides 8c–e (53–62%) and the β- l -nucleosides 9b–e (57–72%), which were transformed to 7-halogenated 7-deazapurine ribonucleosides related to tubercidin and 7-deazainosine. 7-Alkynyl derivatives (1f,g) and (2f,g) were obtained from the 7-iodo nucleosides 1e and 2e employing the palladium-catalyzed Sonogashira cross-coupling reaction. Within the series of 7-deazaadenosine (tubercidin) analogues and 7-deazainosine derivatives physical data such as pKa values, chromatographic mobilities, 13C NMR chemical shifts were determined and correlated to each other.
Qiang Xiao - One of the best experts on this subject based on the ideXlab platform.
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an expeditious total synthesis of 5 deoxy toyocamycin and 5 deoxysangivamycin
Molecules, 2019Co-Authors: Xiangyou Dong, Jie Tang, Jiang Bai, Haixin Ding, Qiang XiaoAbstract:In present paper, an expeditious total synthesis of naturally occurring 5′-deoxytoyocamycin and 5′-deoxysangivamycin was accomplished. Because of the introduction of a benzoyl group at N-6 of 4-amino-5-cyano-6-bromo-pyrrolo[2,3-d]pyrimidine, a Vorbruggen glycosylation with 1,2,3-tri-O-acetyl-5-deoxy-β-D-Ribofuranose afforded a completely regioselective N-9 glycosylation product, which is unambiguously confirmed by X-ray diffraction analysis. All of the involved intermediates were well characterized by various spectra.
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An Expeditious Total Synthesis of 5′-Deoxy-toyocamycin and 5′-Deoxysangivamycin
MDPI AG, 2019Co-Authors: Xiangyou Dong, Jie Tang, Jiang Bai, Haixin Ding, Qiang XiaoAbstract:In present paper, an expeditious total synthesis of naturally occurring 5′-deoxytoyocamycin and 5′-deoxysangivamycin was accomplished. Because of the introduction of a benzoyl group at N-6 of 4-amino-5-cyano-6-bromo-pyrrolo[2,3-d]pyrimidine, a Vorbrüggen glycosylation with 1,2,3-tri-O-acetyl-5-deoxy-β-D-Ribofuranose afforded a completely regioselective N-9 glycosylation product, which is unambiguously confirmed by X-ray diffraction analysis. All of the involved intermediates were well characterized by various spectra
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First total synthesis of kipukasin A
Beilstein-Institut, 2017Co-Authors: Haixin Ding, Zhizhong Ruan, Yirong Zhou, Qiang XiaoAbstract:In this paper, a practical approach for the total synthesis of kipukasin A is presented with 22% overall yield by using tetra-O-acetyl-β-D-ribose as starting material. An improved iodine-promoted acetonide-forming reaction was developed to access 1,2-O-isopropylidene-α-D-Ribofuranose. For the first time, ortho-alkynylbenzoate was used as protecting group for the 5-hydoxy group. After subsequent Vorbrüggen glycosylation, the protecting group could be removed smoothly in the presence of 5 mol % Ph3PAuOTf in dichloromethane to provide kipukasin A in high yield and regioselectivity
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Concise total synthesis of two marine natural nucleosides: trachycladines A and B
Beilstein-Institut, 2014Co-Authors: Haixin Ding, Zhizhong Ruan, Ruchun Yang, Zhijie Mao, Qiang XiaoAbstract:We report the first total synthesis of trachycladines A (10 steps, 34.2% overall yield) and B (11 steps, 35.0% overall yield) by using 5-deoxy-1,2,3-tri-O-acetyl-β-D-Ribofuranose as the starting material. The critical step was the SnCl4 assisted regio- and steroselective deprotection of perbenzylated 1-O-methyl-5-deoxyRibofuranose. The enzyme adenylate deaminase (EC 3.5.4.6) was successfully applied to the chemoenzymatic synthesis of trachycladines B
Maurizio Botta - One of the best experts on this subject based on the ideXlab platform.
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one pot multicomponent synthesis of 2 3 dihydropyrans new access to furanose pyranose 1 3 c c linked disaccharides
Tetrahedron Letters, 2009Co-Authors: Daniele Castagnolo, Lorenzo Botta, Maurizio BottaAbstract:Abstract An efficient synthesis of 2,3-dihydropyrans from different terminal alkynes was developed. The 2,3-dihydropyrans were obtained in a few minutes through a microwave-assisted multicomponent enyne cross-metathesis/hetero-Diels–Alder reaction. Starting from C -ethynyl-Ribofuranose, a new multicomponent approach to furanose–pyranose 1,3-C–C-linked disaccharides was also developed.
Lei Wang - One of the best experts on this subject based on the ideXlab platform.
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structural and genetic characterization of the shigella boydii type 10 and type 6 o antigens
Journal of Bacteriology, 2005Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Lu Feng, Peter R. Reeves, Dan Liu, Jinghua Yang, Qi Jin, Jiansong Cheng, Lei WangAbstract:Comparison of the O antigens of Shigella boydii types 10 and 6 by chemical analysis and nuclear magnetic resonance spectroscopy showed that their structures are similar, with the only difference being the presence or absence of d-Ribofuranose, which is the immunodominant sugar in S. boydii type 10. In S. boydii type 6, a residue previously reported as alpha-d-GlcpA, was shown to be beta-d-GlcpA as in S. boydii type 10. S. boydii types 10 and 6 are reported not to cross-react serologically, and the role of d-Ribofuranose in the specificity of S. boydii was confirmed by making a mutant of type 10 that lacked d-Ribofuranose. However, S. boydii type 11, which has a d-Ribofuranose but with different linkage does show cross-reaction with type 10. The O-antigen gene loci of S. boydii types 10 and 6 were shown to be virtually identical except that orf8 (wbaM), which was confirmed as the ribofuranosyltransferase gene, is interrupted by IS629 in type 6. Therefore, it is proposed that the O-antigen gene cluster of S. boydii type 6 was derived from type 10 by an IS element insertion.
Sachin A Ingale - One of the best experts on this subject based on the ideXlab platform.
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glycosylation of pyrrolo 2 3 d pyrimidines with 1 o acetyl 2 3 5 tri o benzoyl β d Ribofuranose substituents and protecting groups effecting the synthesis of 7 deazapurine ribonucleosides
Journal of Organic Chemistry, 2018Co-Authors: Sachin A Ingale, Peter Leonard, Frank SeelaAbstract:Glycosylation of nonfunctionalized 6-chloro-7-deazapurine with commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-Ribofuranose (45%) followed by amination and deprotection gave tubercidin in only two steps. Similar conditions applied for the synthesis of 7-deazaguanosine employing pivaloylated 2-amino-6-chloro-7-deazapurine gave 18% glycosylation yield. The less bulky isobutyryl or acetyl protected amino group directed the glycosylation toward the exocyclic amino substituent. 7-Halogenated intermediates were glycosylated followed by dehalogenation to overcome the low glycosylation yield in the synthesis of 7-deazaguanosine.
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Glycosylation of Pyrrolo[2,3‑d]pyrimidines with 1‑O‑Acetyl-2,3,5-tri‑O‑benzoyl-β‑d‑Ribofuranose: Substituents and Protecting Groups Effecting the Synthesis of 7‑Deazapurine Ribonucleosides
2018Co-Authors: Sachin A Ingale, Peter Leonard, Frank SeelaAbstract:Glycosylation of nonfunctionalized 6-chloro-7-deazapurine with commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-Ribofuranose (45%) followed by amination and deprotection gave tubercidin in only two steps. Similar conditions applied for the synthesis of 7-deazaguanosine employing pivaloylated 2-amino-6-chloro-7-deazapurine gave 18% glycosylation yield. The less bulky isobutyryl or acetyl protected amino group directed the glycosylation toward the exocyclic amino substituent. 7-Halogenated intermediates were glycosylated followed by dehalogenation to overcome the low glycosylation yield in the synthesis of 7-deazaguanosine
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studies on the glycosylation of pyrrolo 2 3 d pyrimidines with 1 o acetyl 2 3 5 tri o benzoyl beta d Ribofuranose the formation of regioisomers during toyocamycin and 7 deazainosine syntheses
Nucleosides Nucleotides & Nucleic Acids, 2009Co-Authors: Peter Leonard, Sachin A Ingale, Ping Ding, Xin Ming, Frank SeelaAbstract:Glycosylation of silylated 4-amino-6-bromo-5-cyano-7H-pyrrolo[2,3-d]pyrimidine (9) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-Ribofuranose (10) under “one-pot” glycosylation conditions (MeCN, TMSOTf) yielded the N-7 isomer 11 together with the N-1 compound 13 (ratio = 2:1). When the same conditions were applied to 4-hydroxy-7H-pyrrolo[2,3-d]pyrimidine (21) the N-3 isomer 22 was the only glycosylation product formed in almost quantitative yield.
