Methanesulfonic azides

The best enantioselectivities (up to 98.7% ee) were achieved in the case of application of in situ prepared [RuCl (benzene)(5)-SunPhos]Cl as a chiral catalyst. Hydrogenation of (3-keto ester 55 was carried out in EtOH (20 bar of H2, 70° C, 18 hours) with a ratio of substrate/[Ru(benzene) Cl2]2/(5)-SunPhos= 100/0.5/1.1. (3-Hydroxy ester 56 (R = Cbz) was obtained with 96.2% ee. The optical purity of 56 can be improved to 98.9% ee by a single recrystaUization. Enantiopure 56 was transformed into azide 57 in high yield by methanesulfonation/azidation sequence, and the latter was subjected to reduction with hydrogen in the presence of Pd/C followed by deprotection and cyclization to achieve lactame (5)-58 in 90% yield and 98.9% ee. Finally, (S)-7-amino-5-azaspiro[2.4]heptane 59 was obtained in 92% yield by reduction of lactame (5)-58 with LiAIH4 followed by salification in methanol (Scheme 30.12). 

Treatment of 51 with an excess of sodium benzoate in DMF resulted in substitution and elimination, to yield the cyclohexene derivative (228, 36%). The yield was low, but 228 was later shown to be a useful compound for synthesis of carba-oligosaccharides. <9-Deacylation of228 and successive benzylidenation and acetylation gave the alkene 229, which was oxidized with a peroxy acid to give a single epoxide (230) in 60% yield. Treatment of 230 with sodium azide and ammonium chloride in aqueous 2-methoxyeth-anol gave the azide (231,55%) as the major product this was converted into a hydroxyvalidamine derivative in the usual manner. On the other hand, an elimination reaction of the methanesulfonate of 231 with DBU in toluene gave the protected precursor (232, 87%) of 203. 

Methaneperoxoic acid, see Peroxyformic acid, 0419 Methanesulfinyl chloride, 0434 Methanesulfonic acid, 0486 Methanesulfonyl azide, 0464... 

An analogous result was first observed by Thomas <1993S767> and has also been reported elsewhere <2000JME488>. However, in the latter study, the secondary amide was converted into a tetrazole using trifluoro-methanesulfonic anhydride (Tf20) and sodium azide. 

Methyl 4,6-0-benzylidene-3-deoxy-a-D-ribo-hexopyranoside (56) was benzoylated, debenzylidenated, and partially p-toluenesulfon-ylated to 57 this was converted into 58 by reaction with sodium iodide, followed by catalytic reduction. The methanesulfonate of 58 was converted into 59 by reaction with sodium azide in N,N-dimethylformamide, and 59 was converted into 4-azido-3,4,6-trideoxy-a-D-xylo-hexose (60) by acetolysis followed by alkaline hydrolysis. Reduction of 60 with borohydride in methanol afforded 61, which was converted into 62 by successive condensation with acetone, meth-anesulfonylation, and azide exchange. The 4,5-diazido-3,4,5,6-tetra-deoxy-l,2-0-isopropylidene-L-ara/uno-hexitol (62) was reduced with hydrogen in the presence of Raney nickel, the resultant diamine was treated with phosgene in the presence of sodium carbonate, and the product was hydrolyzed under acidic conditions to give 63. The overall yield of 63 from 56 was 4%. The next three reactions (with sodium periodate, the Wittig reaction, and catalytic reduction) were performed without characterization of the intermediate products, and gave (+)-dethiobiotin methyl ester indistinguishable from an authentic sample thereof prepared from (+)-biotin methyl ester. 

Dihydroazocines. Azocines can be converted into the corresponding iminium salts by treatment with 1 equiv of acid, such as methanesulfonic acid, in CHCI3. Nucleophilic additions to iminium salt 226 afforded substituted azocine derivatives reaction with thiophenol in DCM/H20 at room temperature provided 227, while reaction with sodium azide in CHCI3/DMF provided 228 (Scheme 92 <2005EJ01052>). 

Reaction of /3-keto-imide 189 with NaNs in the presence of methanesulfonic acid gave oxazole 192 (Scheme 53) <20000L555>. The azide anion presumably attacks the / -carbonyl group to give 190 followed by loss of N2 and migration to give 191, which is then trapped by the imide carbonyl group. 

The reaction of alcohol (41) with TFAA, followed by treatment with sodium azide, gave (42) in 75% overall yield. The p-toluenesulfonate or methanesulfonate of (41) has also been demonstrated to react with sodium azide affording (42) but in lower yield. Deprotection and subsequent reduction with hydrogen sulfide gave amine (43 Scheme 19). ... 

Sulfonates do not necessarily show the same reaction pattern as halides. It has been reported that p-toluenesulfonate (51a) and methanesulfonate (51b) reacted with azide ion and cyanide ion to give (52a) and (52b), while iodide (51c) gave (53a) and (53b) (Scheme 22). ... 

Reaction with adamantanone. Japanese chemists1 treated adamantanone (1) with sodium azide in methanesulfonic acid with the expectation of achieving the Schmidt reaction. However, the unexpected 4-methylsulfonoxyadamantanone was obtained in 90% yield. Alkaline hydrolysis cleaves (2) to A2-bicyclo[3.3.1]-mmcnc-7-carboxylic acid (3) in 85% yield by a quasi-Favorsky reaction. Adaman-lanc itself does not undergo this unusual substitution reaction. 

Attempted preparation of a frons-related 2-amino-3-thiol derivative from (93) by ammonolysis led, instead, to a polymerized product. Presumably, the sulfide ion formed as the ring opens is a better nucleophile than ammonia, and can attack the starting material. An alternative approach, through an episulfonium ion, was, however, successful for the preparation of 3-amino-2-thiol derivatives having the D-altro configura-tion. Methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside (68) was treated with sodium benzylthiolate, and the product was converted into the 3-methanesulfonate (95). The latter reacted with sodium azide to give the 3-azido-2-benzylthio derivative (97) with retention of configuration, presumably by way of the episulfonium ion (96). The product (97)... 

A similar j8-elimination procedure was applied to a protected D-galac-topyranuronate 4-methanesulfonate by using sodium azide in hexa-methylphosphorie triamide. ... 

Ihe azide Ig was prepared from the methanesulfonic acid ester of the initiator Ib. Nucleophilic displacement of the mesylate group by the azido anion in dimethylsulfoxide leads to the formation of the compound Ig obtained as a yellow oil after purification by column flash chromatography. The structures of the phenones Id-g are in correspondence with the results of the elemental analysis and the spectral data. 

Davis, A. P., Dresen, S. and Lawless, L. J. (1997) Mitsunobu reactions with methanesulfonic acid The replacement of equatorial hydroxyl groups by azide with net retention of configuration. Tetrahedron Lett. 38,4305-4308. 

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