1',2'-Secothymidines. The preparation of 2,3'-anhydro derivatives and the formation of two unusual dimeric products

Cichy, Anne F.; Racha, Saibaba; Subbagh, Hussein I. El; Panzica, Raymond P.; Abushanab, Elie

doi:10.1021/jo00015a017

Cited by 21 publications

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“…Protection of the primary hydroxyl in (−)- 28 as the 3,4-dimethoxybenzyl (DMB) ether was then followed by proteolytic removal of the diethyl ketal to reveal diol (+)- 30 (90% yield, two steps). The best conditions to effect epoxide ring formation proved to be the modified Mitsunobu procedure of Abushanab et al, which effectively furnished epoxide (−)- C , with retention of the C(19) stereogenicity . Fragment (−)- C was thus prepared in three steps and in 79% overall yield from diethyl ketal (−)- 28 .…”

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Total Syntheses of (+)-Zampanolide and (+)-Dactylolide Exploiting a Unified Strategy

2002

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The first total syntheses of (+)-zampanolide (1) and (+)-dactylolide (2), members of a new class of tumor cell growth inhibitory macrolides, have been achieved. Key features of the unified synthetic scheme included the stereocontrolled construction of the cis-2,6-disubstituted tetrahydropyran via a modified Petasis-Ferrier rearrangement, a highly convergent assembly of the macrocyclic domain, and, in the case of zampanolide, a Curtius rearrangement/acylation tactic to install the N-acyl hemiaminal. The complete relative and absolute stereochemistries for both (+)-zampanolide and (+)-dactylolide were also assigned, albeit tentatively in the case of (+)-zampanolide (1).

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Total Syntheses of (+)-Zampanolide and (+)-Dactylolide Exploiting a Unified Strategy

2002

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Synthesis Of Nucleosides

Vorbrüggen¹,

1999

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This chapter deals with the synthesis of nucleosides (e.g., the formation of N ‐glycosides of sugars such as D ‐ribose or 2‐deoxy‐D‐ribose with heterocyclic nitrogen bases). The methods of nucleoside synthesis have been treated in a number of reviews and monographs. It is now generally accepted that nucleosides were among the first organic compounds formed at the start of evolution in the early history of our planet earth. To support this point, guanine and adenine were heated with D ‐ribose in seawater, which contains the Lewis acid magnesium chloride as catalyst. One thus obtained the nucleosides guanosine and adenosine together with comparable yields of unnatural α‐nucleosides. The latter were gradually photoanomerized to the thermodynamically more stable compounds in overall yields of 5–6%. The furanose form of ribose reacts faster than the pyranose form. Corresponding syntheses of the pyrimidine nucleosides uridine and cytidine from uracil , cytosine and ribose are more problematic and remain an enigma. The recent conversion of glycolaldehyde‐ O ‐phosphate and formaldehyde to ribose‐2,4‐di‐ O ‐phosphate might give new insights into the prebiotic syntheses of uridine and cytidine. The evidence and hypotheses for these prebiotic conversions and the evolution of RNA, as well as the implications of an “RNA World,” have been reviewed. These RNA nucleosides are reduced in vivo as 5′‐ O ‐diphosphates by ribonucleotide reductases to the corresponding 2′‐deoxynucleosides—the building blocks of DNA such as 2′‐deoxyguanosine. The thermodynamically controlled synthesis of these four building blocks of RNA has implications for the design of efficient, high yielding, new methods for the synthesis of the naturally occurring nucleosides, nucleoside antibiotics, and modified nucleosides that may serve as antimetabolites to fight viral and parasitic diseases and cancer. The nucleoside rings in this chapter are depicted arbitrarily in the anti conformation, as occurs predominantly in the crystal and solution (based primarily on NOE‐ 1 H‐ and 13 C‐NMR measurements) forms of pyrimidine nucleosides. Only a few nucleosides, such as 6‐methyluridine, occur with the heterocyclic ring predominantly in the syn conformation. The synthesis of C ‐nucleosides has been reviewed previously and is not covered in this review.

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ChemInform Abstract: 1′,2′‐Secothymidines. The Preparation of 2,3′‐Anhydro Derivatives and the Formation of Two Unusual Dimeric Products.

et al. 1991

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1',2'-Secothymidines. The preparation of 2,3'-anhydro derivatives and the formation of two unusual dimeric products

Cited by 21 publications

References 0 publications

Total Syntheses of (+)-Zampanolide and (+)-Dactylolide Exploiting a Unified Strategy

Total Syntheses of (+)-Zampanolide and (+)-Dactylolide Exploiting a Unified Strategy

Synthesis Of Nucleosides

ChemInform Abstract: 1′,2′‐Secothymidines. The Preparation of 2,3′‐Anhydro Derivatives and the Formation of Two Unusual Dimeric Products.

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