A new scalable synthesis of entecavir

Convenient Synthesis of Pyrazolo[4′,3′:5,6]pyrano[4,3-c][1,2]oxazoles via Intramolecular Nitrile Oxide Cycloaddition

“…Fused isoxazoles or isoxazolines obtained by the INOC reaction may also serve as synthetically important intermediates for many biologically active compounds. Such compounds, including the HBV inhibitor entecavir [19,20], the antibiotic branimycin [21], the antiviral (+)-Brefeldin A [22], tricyclic isoxazoles combining serotonin (5-HT) reuptake inhibition with α 2 -adrenoceptor blocking activity [23] and the alkaloids meliacarpinin B [24] and Palhinine A [25], have been synthesized by employing INOC as a key step.…”

Study of the β-oxygen effect in the Barton–McCombie reaction for the total synthesis of (4R,5R)-4-hydroxy-γ-decalactone (Japanese orange fly lactone): a carbohydrate based approach

“…Aer treatment with 60% AcOH: H 2 O, the deoxy methyl glycosides gave lactol ( 14) in 80% yield, 23 which was then oxidised with BAIB/TEMPO to generate the benzyl derivative of Japanese orange y lactone (15) in 84% yield. 24 In methanol, the benzyl ether was cleaved with Pd/C to generate Japanese orange y lactone (1) in 82% yield, 25 which is consistent with analytical results from the isolated natural molecule.…”

Reactivity, Selectivity, and Synthesis of 4‐C‐Silylated Glycosyl Donors and 4‐Deoxy Analogues

“…The 13 C NMR measurements indicated the characteristics of vinylic signals around 115 ppm (SI, Figure S6), originating from the rearrangement of the donor and/or products. This was not unlike vinyl furanoside 25, l-threohex-5-enofuranoside [39,40] observed by glycosylating acceptor 12 directly with 1,6-anhydro compound 4 b (Scheme 4). This vinyl furanoside was also the sole isolated product when 3-deoxy-glucoside donor 6 b was activated with iodine and base.…”