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Synthese von Pyrano[3,2-b][1]benzopyranen aus 1-Nitroglycalen

✍ Scribed by Walter Brade; Andrea Vasella

Publisher
John Wiley and Sons
Year
1990
Tongue
German
Weight
620 KB
Volume
73
Category
Article
ISSN
0018-019X

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✦ Synopsis

Synthesis of Pyranol [3,2‐b][1]benzopyrans from 1‐Nitroglycals

A synthesis of pyrano[3,2‐b][l]benzopyrans β‐addition of salicylic aldehyde to 1‐nitroglycals, followed by a Henry reaction, is described. This sequence gave the cis‐annelated pyranobenzopyranes 9 and 11 from 5 in 54 and 9% yield, respectively, demonstrating the pronounced diastereoselectivity of the β‐addition. Reductive denitration of the crude product mixture yielded 14(75%), 15(15%), and 16(7%), which were oxidized to the aryl ketones 20 and 21, respectively. Reduction of 20 (NaBH~4~) gave exclusively 15. The ketone 20 was deprotected to 22 and 23.

📜 SIMILAR VOLUMES

Kondensierte Furane, XLVII. Synthese von
Kondensierte Furane, XLVII. Synthese von 1H-Pyrano[3,4-b]benzofuran-1-on und Derivaten
✍ Chatterjea, Jnanendra N. ;Sahai, Radhika P. ;Swaroopa, Bipin B. ;Bhakta, Chittar 📂 Article 📅 1980 🏛 Wiley (John Wiley & Sons) 🌐 English ⚖ 353 KB 👁 1 views

**Condensed Furans, XLVII. Synthesis of 1__H__‐Pyrano[3,4‐__b__]benzofuran‐1‐one and their Derivatives** The synthesis of 1__H__‐pyrano[3,4‐__b__]benzofuran‐1‐one derivatives (**6**–**14**) and their 2‐aza‐analogues (**15**–**16**) is described.