Tosyl removal

Benzoyl-6-deoxy-6-iodo-2,3-0-isopropylidene-a-i, - xylohexulofura-nose (47). A solution of 15 grams (31.3 mmole) of 46 in butanone (200 ml.) containing dry sodium iodide (9.3 grams, 62 mmole) was refluxed for 24 hours. The reaction mixture was cooled, the sodium tosylate removed by filtration, and the filtrate concentrated to dryness. The residue was partitioned between water (50 ml.) and chloroform (2 X 50 ml.) the combined chloroform solutions were washed with water, dried over sodium sulfate and concentrated to a colorless sirup which spontaneously crystallized. Recrystallization from aqueous methanol afforded pure material in two crops (11.6 grams, 85%), m.p. 115°-117°C, [ ]D24 + 36.0° (c, 5.3). Anal Calcd. for C16H1906 C, 44.2 H, 4.4 I, 29.3. Found C, 44.3 H, 4.5 I, 29.4. 

Irradiation of chlorobenzene solutions of [Pd(PPh3)4] produces trans-[PdCl2(PPh3)2] and a mixture of chlorobiphenyls, and irradiation of 2-amino-5-iodo-3-(N-methyl-N-tosylamino)pyridine in benzene solution gives 2-amino-3-methylamino-5-phenylpyridine by simultaneous phenylation and tosyl removal. This reaction is a key step in the synthesis of the food-borne carcinogen 2-amino-l-methyl-6-phenylimidazo[4,5-b]pyridine. Substituted 1,2 -biazulenes have been prepared by photolysis of 2-diazo-l,3-dicyanoazulen-6(2H)-one in the presence of azulene derivatives. ... 

Boger s synthesis commenced with the preparation of the left-hand fi agment 155. A sequence of phenol protection of 151, aldehyde oxidation, Curtius rearrangement, tosylation, nitro reduction, Boc protection, and Pb(OAc)4 mediated oxidation afforded quinodiimide 152. A key Diels-Alder reaction gave 153 in good yield. Treatment of 153 in a sequence of oxonolysis, aromatization, Boc deprotection, cyclization to the lactam, A-tosyl removal, indole reduction, and selective Boc protection afforded 154. Conversion of the lactam to the... 

An alternative strategy is to put a 3-(-2-dioxolanyl)ethanoyl substituent in place first and then add the C7-substituent by a Grignard addition. This approach was applied to the synthesis of 8.2C but in this case it was found necessary to remove the tosyl protecting group prior to cyclization[l]. 

Dialkylation of an amine or sulfonamide with a 1,3-dihalide provides a further route to azetidines <79CRV33l, 64HC( 19-2)88 5). Examples of this approach are the formation of N-tosylazetidine from tosylamide and l-bromo-3-chloropropane and the formation of N-alkylazetidinyl esters (36). The latter reaction works well except for R=Me the former provides a useful route to azetidine since the tosyl group can be removed by reductive methods. 

Heplanai (4). To silver tosylate (11 0 g, 38 mmol) in MeCN (100 mL) were added n-lodoheptane 3(7 0 g, 30 mmoO- The mixture protected from light was maintained 24 h at 20°, poured on ice, the product was extracted with El20 and the residua after removal of the solvenL i ias poured Into NasCOg (20 g) in DMSO (150 mL). After healing 5 mm at 1S0°C under N2, the akfehyda was separated as its 2.4-dimtrophenylhydrazone (DNPH) to afford 6.9 g of 4 DNPH (70%), mp 106-107 0. 

The tosyl group has also been removed by reductive cleavage with Na/NH3 (65-73% yield), Na/naphthalene (50-87% yield),and Na(Hg)/MeOH (96.7% yield)."... 

Sodium naphthalenide. This reagent has been used to remove the tosyl group from an amide. ... 

Cram and Hogberg have prepared a number of compounds similar to 3, utilizing mesyl and tosyl as protecting groups. These syntheses are generally unequivocal, but removal of the sulfonamide has proved troublesome (see also Sect. 4.5). 

A solution of 3jS-hydroxy-5a-androstan-17-one tosylate (193, 60 mg) in tetrahydrofuran (10 ml, freshly distilled from lithium aluminum hydride) is added dropwise to a boiling suspension of lithium aluminum deuteride (60 mg) in tetrahydrofuran (10 ml). The resulting suspension is heated under reflux for 30 min and after cooling the excess reagent is decomposed by the careful addition of a few drops of water. The heating is continued for a few minutes to coagulate the inorganic salts which are removed by filtration... 

The primary amine of an amino acid as its tosylate salt can be protected by coordination with a crown ether. The protection scheme was sufficient to allow the HOBt/DDC coupling of amino acids. The crown is removed by treatment with diisopropylethylamine or KCl solution. 

Electrolysis, Me4N Cl , 5°, 65-98% yield. " Acylation of a tosylated amine with BOC or benzoyl reduces the potential required for electrolytic cleavage so that these aryltosyl groups can be selectively removed in the presence of a simple tosylamide. °... 

Tile easy availability of (di)nitronaphthyridones, in which the lactam part can easily be converted into an iminochloride, has successfully led to preparation of the parent (di)nitronaphthyridines by removal of the chloro atom. For that purpose the chloro atom in the 2- and 4-chloro derivative of the 3-nitro-l,5-, -1,6-, and -1,8-naphthyridines (78a-78e) was first substituted with tosylhydrazine to give the corresponding tosyl-hydrazide, which then was hydrolyzed in alkaline solution into the corresponding 3-nitro-l,5-, -1,6-, and -1,8-naphthyridines (79a, 79b, and 79c). 

Dimethyl-l-tosyl-6,7-dihydro-l//-l,2-diazepine (1.164 g, 4.19 mmol) was added to NaOEt prepared from Na (0.16 g, 6.96 m-atom) and EtOH (20 mL). The solvent was removed on a rotary evaporator at... 

It should be noted that the sense of asymmetric induction in the lithiation/ rearrangement of aziridines 274, 276, and 279 by treatment with s-butyllithium/ (-)-sparteine is opposite to that observed for the corresponding epoxides (i.e. removal of the proton occurs at the (S)-stereocenter) [102], If one accepts the proposed model to explain the selective abstraction of the proton at the (R) -stereo-center of an epoxide (Figure 5.1), then, from the large difference in steric bulk (and Lewis basicity) between an oxygen atom and a tosyl-protected nitrogen atom, it is obvious that this model cannot be applied to the analogous aziridines. 

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