Nosyl chloride

Representative Procedure for Nosyl Chloride Promoted Glycosylation with Cl-Hemiacetal Donors 130... 

The synthesis of the dideoxyribonucleosides was achieved by glycosylating the anion of 275 with 5-0-[(/-butyl)dimethylsilyl]dideoxypentofura-nosyl chloride (276) to give the regioisomeric nucleosides 277-279. TVeat-ment of the desilylated products 286-282 with aqueous NaOH gave... 

To a stirred solution of 1,3-diamine-2-hydroxy propane (58.8 mmol) and K2CO3 (155.8 mmol) dissolved in 100 ml of water at 0°C was added dropwise p-nosyl chloride (132.1 mmol) dissolved in 60 ml THE. Thereafter the solution was stirred at ambient temperature overnight and then concentrated. The product was purified by chromatography on silica using EtOAc/hexanes, 1 1, re-crystallized in acetone/hexanes, and isolated in 95% yield, mp = 210-212 °C (sub). H- and H-NMR data supplied. 

The mercury derivatives procedure has also been applied to deoxynucleosides. 2 -Deoxy-adenosine and its a-D-anomer are obtained, after deblocking, from the AT-glycosylation of chloromercurio-7V -benzyladenine with crystalline 2-deoxy-3,5-di-0-(4-toluoyl)- -D-ribofura-nosyl chloride. 

The preparation of chloromercurio derivatives of the purines presents some difficulties. A method for circumventing this problem has been found with the use of mercury(II) cyanide or mercury(II) acetate as a condensation catalyst.The use of mercury(ll) cyanide also simplified the synthesis of guanine nucleosides. Treatment of 6-chloropurin-2-amine with excess hexamethyidisilazane, followed by treatment with 2-deoxy-3,5-di-C>-(4-toluoyl)-a-D-ribofura-nosyl chloride and mercury(ll) cyanide in benzene and finally deprotection of the resulting protected a- and )S-anomeric nucleosides 7 provides an elTicicnt synthesis of a- and )S-2 -de-... 

The chlorosulfated glycosyl chloride 60 is converted into 2-chloro-2-deoxy-a-D-lyxopyra-nosyl chloride 61 when treated with aluminum chloride (O Scheme 34) [58]. This reaction proceeds via an initial intramolecular displacement of chlorosulfate at C-2 by the anomeric chlorine atom, followed by the chloride ion attack at the more highly reactive center (C-1). Pyranoid derivatives having a chlorosulfonyloxy group in a frawi -diaxial relation with a ring proton, such as 62, may undergo an elimination reaction to yield the unsaturated compound 63 (O Scheme 35) [59]. 

Problems may also occur during the installation of the nosyl moiety during the reaction of a primary amine 1 and nosyl chloride 2c.2b A cyclic Meisenheimer complex 39 is formed followed by loss of S02 to give nitro aniline 40 as a minor product during nosylation. None of this side product is observed with the less reactive mono-nitro... 

O-Isopropylidene, 5-tosyl 2,3-O-Iso-propylidene-5-O-tosyl-a-L-rhamnofura-nosyl chloride. 6-Deoxy-2,3-0-isopropylidene-5-O-tosyl-a-L-mannofura-nosyl chloride [32658-92-7]... 

Cesium acetate was further used to convert a secondary alcohol in the synthesis of (—)-dysiherbaine, a natural product isolated from a marine sponge shown to act as a neurotoxin. In this case, the alcohol to be inverted was first converted into a nosylate using nosyl chloride, DMAP, and triethyl ammonia. The following application of cesium acetate was then used without the addition of crown ether, yielding the inverted alcohol after hydrolysis with potassium carbonate in sodium bicarbonate and methanol (eq 3). Importantly, cesium acetate did not interfere with the epoxide or olefin present in the natural product precursor. ... 

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