Desoxy‐nitrozucker. 3. Mitteilung. Synthese von Ketosen durch Kettenverlängerung von 1‐Desoxy‐1‐nitro‐aldosen. Nucleophile Additionen und Solvolyse von Nitroaethern

Abstract

Synthesis of Ketoses by Chain Elongation of 1‐Deoxy‐1‐nitroaldoses. Nucleophilic Additions and Solvolysis of Nitro Ethers A method for the preparation of chain elongated uloses based upon the base‐catalyzed addition of 1‐deoxy‐1‐nitroaldoses to aldehydes and Michael acceptors and subsequent solvolytic replacement of the nitro group by a hydroxy group is described. Thus, addition of 1 , 3 and 9 to formaldehyde, followed by solvolysis gave the chain elongated ulose derivatives 2 , 8 and 10 (63–76%), respectively. The configuration at the anomeric center of the addition products was deduced from 13 C – NMR . spectra and mutarotation. In the case of 3 , the primary addition products 4 and 6 were isolated and acetylated to 5 and 7 . The nitro derivatives 4 – 7 do not follow Hudson 's rule of isorotation. Addition of 1 to benzaldehyde (44%) and to nonanal (74%) preceded with a small degree of diastereoselectivity to give 15a / 15b , and 11 / 12 , respectively. The configuration of the secondary hydroxyl group of 12 was determined by correlation with methyl 2‐hydroxydecanoate ( 14 ). Addition of 1 to the galacroaldehyde 16 gave a single compound 17 (78%). The structure of this dodecosulose was determined by X‐ray crystallography. Solvolysis of the acetylation product 18 in formamide gave the hemiacetal 19 (69%). Michael addition of 1 to acrylonitrile, methyl vinyl ketone and cyclohexenone under solvolytic conditions gave the hemiacetals 27 , 30 and 31a , b (49%, 71% and 76%, respectively). Under non‐solvolytic conditions (Bu 4 NF), 1 reacted with acrylonitrile, and crotononitrile to give the anomeric nitro ethers 23 and 24 (67%) and 25 and 26 (84%). respectively. Similarly. 3 added to acrylonitrile to give 28 and 29 (55%, 4:1). This reaction appears to proceed under kinetic control. Addition of 1 to ethyl propiolate and solvolysis yielded the unsaturated spirolactone 32 (50%) and the hemiacetal 33 (17%). Hydrogenation of 32 gave the saturated spirolactone 34 (100%) which was also obtained from 1 and methyl acrylate (63%). Addition of 1 to dimethylmaleate gave the unsaturated ester 35 (48%).