Mesyl with cyanide

An unusual stereospecific ring contraction has been observed upon attempted substitution of 4-0-activated pentono-1,5-lactams with cyanide. The reaction of 4-0-methanesulfonyl-2,3-0-isopropylidene-D-ribo- or -D-lyxo-1,5-lactams with tetrabutylammonium cyanide gave 4-amino-5-C-cyano-4,5-dideoxy-2,3-0-iso-propylidene-L-lyxo- or -L-ribo-l,4-lactams respectively (Scheme 16), instead of the expected products of simple Sn displacement of mesylate by cyanide. Reduc-... 

The imidazopyridine 123 was synthesized by treating amino acid 122 with p-toluenesulfonyl cyanide and DCC. The yield of 123 was lower (38%) when the mtinchnone was generated with mesyl chloride (72). The minor amide product 124 is proposed to arise from the diastereoisomeric mtinchnone adduct that undergoes fragmentation rather than decarboxylation. 

Quallich and Woodall described the first asymmetric synthesis utilizing a catalytic enantioselective reduction of the ketoester 35 with (S)-terahydro-l-methyl-3,3-diphenyl-lH,3W-pyrrolo[l,2-c][l,3.2]oxazaborole (CBS) to give the desired hydroxyester 36 (90% ee). After mesylation, Sn2 displacement with a higher-order cuprate derived from copper cyanide gave the diaryl r-butyl ester 37 with good chirality transfer. Intramolecular Friedel-Crafts cyclization gave the tetralone 31 in 90% ee (Scheme 7). ... 

Servis conditions. The resulting mesylate reacted with excess sodium cyanide in N.N -dimclhylproplcnurea (DPMU) to give the nitrile. The intramolecular Friedel-Crafts type cyclization of the hydrolysis product acid 361 provided... 

An efficient route to 4-aryloxy pyrazoles 353 bearing a trifluoromethyl group has been developed from 4-hydroxypyrazole 351 and 3,5-dicyanofluorobenzene 352 under basic conditions, with concomitant removal of the silyl group (Scheme 34) <2006SL1404>. Removal of the AT-hydroxyethyl group was achieved by a two-step protocol involving mesylation followed by treatment with sodium cyanide at elevated temperatures, resulting in the formation of the dealkylated compound 354. 

The general techniques used were also applied to the synthesis of natural alkaloids in the quebrachamine and Aspidosperma series (233). The oxidative cyclization step in the previous step proceeded in only 30-40% yield. In order to improve this process, a more reactive intermediate was used. Condensation of tryptamine with the highly reactive aldehyde-ester 529 gave the lactam 530 as a mixture of C-3 isomers in 90% yield. Lithium aluminum hydride reduction, catalytic reduction, and mesylation gave the familiar mesylate salt 486. Nucleophilic attack by cyanide ion in dimethyl-formamide produced the nine-membered ring intermediates 531 and 532. Hydrolysis and methylation with diazomethane gave vincadine (185) and... 

The pure Iran -isomer (236) which was isolated in 20% yield was converted to its mesylate (237). Reaction of 237 with p-chlorothiophenol (238) in the presence of trieth-ylamine and EtOH under reflux gave an 5-alkylated compound (239), which on heating with cuprous cyanide in DMF furnished a cyano compound (240). Reduction of 240 with sodium borohydride-borontrifluoride etherate yielded an aminomethyl compound (241) in 20% yield. Finally, treatment of 241 with triphosgene followed by iV-methylhydroxyl-amine hydrochloride in the presence of triethylamine afforded the target compound (229), (Scheme 30.41). 

Now let us see the behaviour of the mesylates of the isomers 4 and 5. Firstly the cis isomer (3 ) was reacted with sodium cyanide, in boiling methanol. The expected nitrile (7) could be isolated only as a minor product, in about 1 % yield. The rearranged product 6 has been formed as a main product in 73 % yield. In addition to... 

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