Stereoselective synthesis of pyrrolo[2,3-d]pyrimidine α- and β-D-ribonucleosides from anomerically pure D-ribofuranosyl chlorides: Solid-Liquid Phase-Transfer Glycosylation and 15N-NMR Spectra
✍ Scribed by Helmut Rosemeyer; Frank Seela
- Publisher
- John Wiley and Sons
- Year
- 1988
- Tongue
- German
- Weight
- 710 KB
- Volume
- 71
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Solid-liquid phase-transfer glycosylation (KOH, tris[2-(2-methoxyethoxy)ethyl]amine ( = TDA-I ), MeCN) of pyrrolo[2,3-djpyrimidines such as 3a and 3b with an equimolar amount of 5-U-[( 1, I-dimethylethy1)dimethylsilyl~-2,3-U-(l-methylethylidene)-a -D-ribofuranosyl chloride (1) [6] gave the protected 8-o-nucleosides 4a and 4b, respectively, stereoselectively (Scheme). The B-o-anomer 2 [6] yielded the corresponding a -D-nucleosides 5a and 5b with traces of the 8-D-compounds. The 6-substituted 7-deazapurine nucleosides 6a, 7a, and 8 were converted into tubercidin (10) or its a -D-anomer (1 1). Spin-lattice relaxation measurements of anomeric ribonucleosides revealed that T , values of H-C(8) in the a-o-series are significantly increased compared to H-C(8) in the B-D-series while the opposite is true for T , of H-C(1'). I5N-NMR data of 6-substituted 7-deazapurine o-rihofuranosides were assigned and compared with those of 2'-deoxy compounds. Furthermore, it was shown that 7-deaza-2'-deoxyadenosine ( = 2'-deoxytubercidin; 12) is protonated at N( l), whereas the protonation site of 7-deaza-2'deoxyguanosine (20) is N(3). ') Purine numbering as indicated in Formulae 3a and 13 is used throughout the manuscript, except within the Exper. Part ; Tables 1 4 provide purine as well as pyrrolo[2,3-d]pyrimidine (see Formula 10) numberings.