Synthesis of carbasugars from aldonolactones. Part II. Preparation of polyhydroxy/aminocyclopentanes functionalised at all five ring carbons

A Study on the Allylic Substitution of (1R,5R,8R)- and (1R,5R,8S)-8-Hydroxy-2-oxabicyclo[3.3.0]oct-6-en-3-one Derivatives − Preparation of (1S,2R,3R)-9-[2-Hydroxy-3-(2-hydroxyethyl)cyclopent-4-en-1-yl]-9H-adenine

“…[10] In order to investigate the effect of the bicyclic system, we decided to prepare both the acetate and the more reactive carbonate derivative, as well as the C-8 epimeric acetate and carbonate. Thus, the allylic acetate 2 was deprotected by treatment with acidic methanol to give the allylic alcohol 3 (Scheme 2).…”

“…Pyridine (5 mL) and methyl chloroformate (1.22 mL, 15.85 mmol) were added to a solution of compound 3 [10] (739 mg, 5.28 mmol) in dichloromethane (50 mL) at 0°C and the mixture was stirred for 30 min. Water (10 mL) was then added, and the mixture was stirred for 10 min, followed by addition of more water (15 mL).…”

“…NaHCO 3 (20 mL), and brine (20 mL), followed by drying (MgSO 4 ) and concentration. Purification by flash chromatography (EtOAc/hexane, 1:1) gave the title compound 7 as a colorless oil, which crystallized upon standing [10] (101 mg, 0.55 mmol) in THF (2 mL), and the resulting yellow reaction mixture was stirred for 16 h at room temp. The now brown reaction mixture was quenched with 10% aqueous acetic acid (5 mL) and stirred for 15 min.…”

“…[7,8] Starting from bromodeoxyaldonolactones, very useful synthons themselves for a number of applications, [9] these bicyclic lactones have been converted into a number of carbasugars and aminopolyhydroxycyclopentanes. [7,8,10,11] In particular, we have utilized the lactone 2 for the synthesis of carbasugars functionalized at all five ring carbon atoms. [10] tures of both C-6 and C-8 substituted products, thus limiting the synthetic use of the reaction with these nucleophiles.…”

“…[7,8,10,11] In particular, we have utilized the lactone 2 for the synthesis of carbasugars functionalized at all five ring carbon atoms. [10] tures of both C-6 and C-8 substituted products, thus limiting the synthetic use of the reaction with these nucleophiles. Additionally, Mitsunobu substitution of (1R,5R,8R)-8-hydroxy-2-oxabicyclo [3.3.0]oct-6-en-3-one (3) with 6-chloropurine, followed by reduction of the lactone moiety and treatment with liquid ammonia, gave the carbocyclic nucleoside (1S,2R,3R)-9-[2-hydroxy-3-(2-hydroxyethyl)cyclopent-4-en-1-yl]-9H-adenine (19), which can be viewed as an analogue of the carbocyclic nucleoside BCA.…”