Mesyl group

Chemical Properties. Methanesulfonyl chloride (MSC) is a reactive chemical which allows iatroduction of the mesyl group, CH SO, into a... 

The mesylate group, introduced with methanesulfonyl chloride, can be cleaved with lithium aluminum hydride and dissolving metal reduction (Na, /-BuOH, HMPT, NH3, 64% yield). ... 

In contrast to the usual behavior, replacement of the mesyl group in 2 O mesyl-3-diallylaminodeoxy-a-D-altropyranoside by treatment with triethylamine trihydrofluonde leads to, because of neighboring-group participation, the fluori-nated product with retention of configuration [45] (equation 33)... 

Activity is also retained when oxygen at the 21 position is replaced by sulfur. Preparation of one of these compounds follows a route quite analogous to the foregoing thus, displacement of the mesylate group in the cortisone (56) derivative 57 with the anion from thiopivalic acid affords thioester 58. Reduction of the 11-ketone by means of borohydride affords tixocortol pivalate (59)[13j. 

In view of the unexpected effects of the C-2 and C-3 substituents on the reaction of C-4 sulfonates, it is worthwhile to point out the observations made with some 2,3-dideoxy derivatives. Treatment of ethyl 2,3-dideoxy-4,6-di-0-methylsulfonyl-D-ert/ hro-hexopyranoside (40) with sodium iodide and acetone at 115°C. caused the displacement of the C-6 mesylate group selectively to give 41. Catalytic hydrogenation then gave the corresponding ethyl 4-0-methylsulfonyl-2,3,6-trideoxy- -D-en/ /iro-hexoside in good overall yield (83%) (72). 

The earliest method developed for the preparation of nonracemic aziridine-2-car-boxylates was the cyclization of naturally occurring (3-hydroxy-a-amino acid derivatives (serine or threonine) [4]. The (3-hydroxy group is normally activated as a tosyl or mesyl group, which is ideal for an intramolecular SN2 displacement. The cyclization has been developed in both one-pot and stepwise fashion [4—9]. As an example, serine ester 3 (Scheme 3.2) was treated with tosyl chloride in the presence of triethylamine to afford aziridine-2-carboxylate 4 in 71% yield [9]. Cyclization of a-hydroxy- 3-amino esters to aziridine-2-carboxylates under similar conditions has also been described [10]. 

The cyclic kotal (19) was again used as protection and the methane sulphonyl (MeSOg or Ms, mesylate) group was used as the leaving group X (p T2S) (20). The protecting group was left in until the end to avoid any side reactions. 

Methanesulfonyl group is called a mesyl group and /7-toluenesulfonyl group is... 

Stereospecific contraction of the seven-membered nucleus was observed on treatment of the dimesylated thiepanetetrol derivatives 67 (obtained in turn from d-sorbitol) with sodium azide to give a 5 1 mixture of the bis(azido)tetrahydrothiophenes 68 and 69. Intramolecular nucleophilic displacement of either mesylate group initiates this ring contraction <00TA1389>. 

When the nucleophile bears an appropriately unsaturated chain, these enantioselective cyclizations can be used to advantage in tandem processes leading to bicyclic systems (Scheme 42) [131,141,142], The greater enantios-electivity observed with the mesylate group in this example may be due to the lower degree of stabilization of the alkene radical cation in the looser ion pair, which leads to more rapid cyclization. 

Alcohol 1149 unexpectedly gave mesylate 1150 upon treatment with MsCl. The mesylate group could be displaced with methanethiolate to give 1151, also prepared from alcohol 1152 via 1153 [93JCS(P1)1109]. 

The synthesis of isomeric DL-allitol succeeded when the hydroxyl groups in cts,cis-2,4-hexadiene-l,6-diol were protected with benzoyl or mesyl groups. Epoxidation gave the appropriate derivatives of 2,3 4,5-dianhydro-DL-allitol (16%), which were then reduced with lithium aluminum hydride to DL-crt/f/iro-2,5-hexanediol. 

Reaction of the mesylated lignin prepared in step 1 (Fig. 1) with the polystyryl carbanion (living polystyrene) from step 2 (Fig. 2). The carbanion displaces the mesylate groups on the lignin in a nucleophilic displacement reaction with the formation of the polystyrene-lignin graft copolymer (Fig. 3). 

H-NMR (d6-DMSO) 8 3.51 (s, PEG backbone) absence of peak at 4.31 ppm (t, —CH20S02—) indicated all mesylate groups had been substituted... 

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