Robert S. Klein

Synthesis of “9-deazaadenosine”; A new cytotoxic C-nucleoside isostere of adenosine

Abstract The synthesis of 7-(β- D -ribofuranosyl)-4-amino-5H-pyrrolo[3,2- d ]pyrimidine (9-deazaadenosine) 9 is described. It involves base-catalyzed cyclization of N-carboethoxyenamine 4 to give β- and α-ribosylated 3-amino-2-cyanopyrroles 6 and 7 , respectively, followed by a one-step conversion to the desired pyrrolo[3,2- d ]pyrimidine system.

Synthesis of the pyrrolo[3,2-d]pyrimidine C-nucleoside isostere of inosine

Abstract The synthesis of “9-deazainosine,” a new C-nucleoside analog of inosine and of formycin B is described. It involves conversion of a ribosylated 3-amino-2-carboalkoxypyrrole intermediate to the desired pyrrolo[3,2-d]pyrimidine system.

Nucleosides LXXXIX. Synthesis of 1-(2-chloro-2-deoxy-α- and -β-D-arabinofuranosyl)cytosines☆

1-(2-Chloro-2-deoxy-β-D-arabinofuranosyl)cytosine (16) and its α anomer (18) were synthesized by direct condensation of 3,5-di-O-acetyl-2-chloro-2-deoxy-α-D-arabinofuranosyl bromide with trimethylsilylated N4-acetylcytosine in the absence of catalyst. A new and convenient method for the synthesis of 1,3,5-tri-O-acetyl-2-chloro-2-deoxy-α-D-arabinofuranose from methyl 3,5-di-O-benzyl-α,β-D-ribofuranoside is described.

C-Glycosylation of substituted heterocycles under Friedel-Crafts conditions. I: A two-step synthesis of the thieno[3,4-d]pyrimidine C-nucleoside analog of inosine

Abstract Direct stannic chloride catalyzed C-glycosylation of N-formyl-4-amino-3-carboalkoxy thiophenes with 1- O -acetyl-tri- O -benzoyl-β- D -ribofuranose, followed by annelation of a fused pyrimidone ring upon treatment with ammonia, constitutes a short approach to the synthesis of a new C-nucleoside inosine analog.

Synthesis of furo[3,2-d]pyrimidine nucleosides: A novel c-nucleoside isostere of adenosine

Abstract The synthesis of 4-amino-7-(β- D-ribofuranosyl)-furo[3,2- d ]pyrimidine, a new C-nucleoside analogof adenosine, is described. It involves base-catalyzed cyclization of the 2-(ribofuranosyl)-2-cyano ethers 3 to afford the ribosyl-3-amino-2-cyanofurans 4a and 4β, followed by a two step conversion into the desired furo[3,2- d ]pyrimidine system.

Nucleosides 137. Synthetic Modifications at the 2′Position of Pyrrolo[3,2-D]Pyrimidine and Thieno[3,2-D]Pyrimidine C-Nucleosides, Synthesis of “2′-Deoxy-9-Deazzadenosine” and of “9-Deaza ARA-A”

Abstract The syntheses and preliminary biological evaluation of several novel pyrrolo[3,2-d]pyrimidine and thieno[3,2-d]pyrimidine C-nucleosides incorporating the arabinofuranosyl or 2′-deoxyribofuranosyl sugar moiety are described. The 2′-deoxy thieno[3,2-d]pyrimidine C-nucleosides (15 and 16) were obtained from 7-(β-D-ribofuranosyl)-4-oxo-3H-thieno[3,2-d]pyrimidine (3) and its 4-SMe derivative 8. “2”-Deoxy-9-deazaadenosine (31), “9-Deaza ara-A” (38) and the 2′-substituted arabinosyl pyrrolo[3,2-d]pyrimidine C-nucleosides (42 - 44) were synthesized from 4-amino-7-(2,3-O-isopropylidene-5-O-trityl-β-D-ribofuranosyl)-5H-pyrrolo[3,2-d]pyrimidine (21)

NUCLEOSIDES PART 93, SYNTHESIS OF 6‐BETA‐D‐RIBOFURANOSYL‐PYRIMIDINES, A NEW CLASS OF PYRIMIDINE C‐NUCLEOSIDES

Aus dem geschutzen Ribosederivat (Ia) entsteht das Chlorid (Ib), das mit Silberpropiolat (II) zum Addukt (III) fuhrt.