Abstract:Hydroformylation of 3,4-di-0-acetyl-~-xylal gave 4,5-di-0-acetyl-2,6-anhydro-3-deoxyaldehyde-D-lyxo-hexose (I) and 4,5-di-0-acetyl-2,6-a1~hydro-3-deoxy-uldehydo-~-xylo-hexose iII). llethyl sulfoxide oxidation of 2,3-di-0-acet~~1-1,5-anhydro-4-deoxy-~-u~ubino-hexitol (111) and of 2,3-di-0-acetyl-l,5-anhl-dro-L-xylo-hex (IV) yielded compoullds I and 11, respectively.Reaction of 3,4,6-tri-0-acetyl-D-glucal with carbon inonoxide and hydrogen under carefully controlled conditions yielded 4,5,7-tri-0-acetyl-2,6-anhy… Show more
“…Rosenthal has studied the hydroformylation of 3,4,6-tri- O -acetyl- d -glucal ( 1 ) using [Co 2 (CO) 8 ] as catalyst and has obtained an α/β mixture of the 1-hydroxymethyl-2-deoxy carbohydrates 2 and 3 in drastic conditions of pressure and temperature. When the gas consumption was strictly controlled, aldehydes 4 and 5 were preferentially obtained, but always as an α/β mixture (Scheme ). 1 …”
The hydroformylation of the differently protected glucal derivatives 3,4,6-tri-O-acetyl-Dglucal, 3,4,6-tri-O-benzyl-D-glucal and 3,4,6-tri-O-methyl-D-glucal was carried out with rhodium catalytic systems, and 2-formyl derivatives were obtained as the main products in yields of 58%, 68%, and 55% respectively, when [Rh 2 (µ-OMe) 2 (COD) 2 ]/P(O-o-t BuC 6 H 4 ) 3 was used. The bulky phosphite needs to be used as auxiliary ligand to achieve the hydroformylation of these highly hindered cyclic olefins. A mechanistic cycle is proposed which explains the regio-and stereoselectivity of the reaction. The mononuclear rhodium complex trans-[RhCl(CO)(P(O-o-t BuC 6 H 4 ) 3 ) 2 ] was isolated at the end of the catalytic reaction by breaking the dinuclear complexes used as catalyst precursors. To confirm the characterization of trans-[RhCl(CO)(P(O-o-t BuC 6 H 4 ) 3 ) 2 ], a separate synthesis was carried out which isolated crystals suitable for an X-ray determination.
“…Rosenthal has studied the hydroformylation of 3,4,6-tri- O -acetyl- d -glucal ( 1 ) using [Co 2 (CO) 8 ] as catalyst and has obtained an α/β mixture of the 1-hydroxymethyl-2-deoxy carbohydrates 2 and 3 in drastic conditions of pressure and temperature. When the gas consumption was strictly controlled, aldehydes 4 and 5 were preferentially obtained, but always as an α/β mixture (Scheme ). 1 …”
The hydroformylation of the differently protected glucal derivatives 3,4,6-tri-O-acetyl-Dglucal, 3,4,6-tri-O-benzyl-D-glucal and 3,4,6-tri-O-methyl-D-glucal was carried out with rhodium catalytic systems, and 2-formyl derivatives were obtained as the main products in yields of 58%, 68%, and 55% respectively, when [Rh 2 (µ-OMe) 2 (COD) 2 ]/P(O-o-t BuC 6 H 4 ) 3 was used. The bulky phosphite needs to be used as auxiliary ligand to achieve the hydroformylation of these highly hindered cyclic olefins. A mechanistic cycle is proposed which explains the regio-and stereoselectivity of the reaction. The mononuclear rhodium complex trans-[RhCl(CO)(P(O-o-t BuC 6 H 4 ) 3 ) 2 ] was isolated at the end of the catalytic reaction by breaking the dinuclear complexes used as catalyst precursors. To confirm the characterization of trans-[RhCl(CO)(P(O-o-t BuC 6 H 4 ) 3 ) 2 ], a separate synthesis was carried out which isolated crystals suitable for an X-ray determination.
“…Two other recently reported routes to Type B branched-chain sugars involve the application of the 0x0 reaction to unsaturated carbohydrates (8), and the synthesis of cyanodeoxy sugars by the opening of carbohydrate epoxides (9). The preparation of branched-chain dinitro sugar derivatives, namely methyl 4,6-0-benzylidene-2,3-dideoxy-3-nitro-2-nitroalkyl-~~-glucopyranosides and methyl 4,6-0-benzylidene-2,3-dideoxy-3-nitro-2-nitroalkyl-VD-galactopyranosides, by Michael addition has been reported also (10).…”
Addition of nitryl iodide to 3 -d e o x y -1 , 2 : 5 , 6 -d i -0 -i s o p r o p y l i d e n e -3 -~r a n o s e (2), followed by treatment of the product with sodium borohydride, gave crystalline 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-nitromethyl-a-~-aofuranose (3); the branched-chain unsaturated sugar (2) was prepared by way of a Wittig reaction with 1,2:5,6-di-O-isopropylidene-a-o-ribo-hexofuran0s-3-ul0se (1). Acid-catalyzed hydrolysis of 3 afforded 3-deoxy-3-C-nitromethyl-D-allose, which exists predominantly in the P-D-furanose form (4).L'addition d'iodure de nitryle au 3-deoxy-1,2:5,6-di-O-isopropylid~ne-3-methylene-~-~-ribo-hexofuranose (2), le produit obtenu etant trait6 au borohydrure de sodium, donne le 3-desoxy-1,2:5,6-di-0-isopropylidene-3-C-nitromethyl-a-D-allofuranose cristallis6 (3); le sucre a double liaison exocyclique (2) a ete prepare par reaction de Wittig par le 1,2:5,6-di-O-isopropylidene-a-~-ribo-hexofuranos-3-ulose (1). L'hydrolyse catalysee par les acides de 3 conduit au 3-desoxy-3-C-nitromethyl-D-allose, qui existe de maniQe predominante sous la fornie J3-D-furanose (4).
The use of dimethyl sulfoxide as an oxidizing agent began with the discoveries by Kornblum and co‐workers that certain α‐bromo ketones were converted into glyoxals under mild conditions by treatment with dimethyl sulfoxide, and that primary tosylates such as
n
‐octyl tosylate were converted into the corresponding aldehydes using dimethyl sulfoxide and sodium bicarbonate at 150° for 3 minutes. The initial step of the reactions involves a displacement by dimethyl sulfoxide giving an alkoxysulfonium ion and this species undergoes a 1,2 elimination assisted by base to give the carbonyl product
A few years later it was discovered that alcohols were oxidized at room temperature to carbonyl compounds by dimethyl sulfoxide, dicyclohexylcarbodiimide (DCC), and phosphoric acid. This reaction was immediately recognized as an effective and mild procedure for sensitive substrates, and the extensive studies by this group and the development of alternative variations elsewhere have been the subject of several earlier reviews.
The course of the Moffatt procedure is summarized. The key intermediate in this process is the oxysulfonium ylide, which appears to be common to all of the variations of dimethyl sulfoxide oxidations, and which reacts intramolecularly to give the products.
Other related procedures that were soon developed utilize dimethyl sulfoxide activated by acetic anhydride, phosphorus pentoxide, sulfur trioxide/pyridine complex, and chlorine. Reaction of alcohols with phosgene to give chloroformates which react with dimethyl sulfoxide to give alkoxysulfonium ions, followed by reaction with triethylamine, also effects oxidation.
The reaction of the complexes of dimethyl sulfide and chlorine or
N
‐chlorosuccinimide (NCS) with alcohols is proposed to give the same alkoxysulfonium complexes, which are efficiently converted into carbonyl products upon addition of triethylamine. Electrochemical activation of sulfides has also been successfully utilized.
The activation of dimethyl sulfoxide is effected by many reagents, and these reactions as well as those involving activated sulfides evidently involve the alkoxysulfonium ion and the decisive oxidation step which occurs via the alkoxysulfonium ylide in all the reactions. Activation of dimethyl sulfoxide by oxalyl chloride, has become the most used of these oxidation procedures, but several of the other methods are also convenient and efficient.
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