N-Tosyl

The N—CO distance of 1.38 A in (58) is rather greater than that of a normal amide (ca. 1.32 A) this has been attributed to ring strain and to inhibition of normal amide resonance by interaction with the N-aryl substituent. This inhibition of resonance is more pronounced in the N-tosyl-4-thioxoazetidin-2-one (59), which exhibits very short C=0 and C=S distances as well as the unusually long C—N bonds (80TL4247). NMR investigations... 

Dissolve in Et20, dry over KOH and distil. The N-Tosyl derivative has m 134-135° (from EtOH). [Chem Ber 96 550 1963.]... 

It is interesting to note that although the first examples of template effects were observed in nitrogen macrocycles (see chapter 2) no template effect appears to operate in the synthesis of 72. Richman and Atkins note this in their original report . The authors replaced the sodium cation with tetramethylammonium cations and still obtained greater than 50% yield of tetra-N-tosyl-72. Shaw considered this problem and suggested that because of the bulky N-tosyl groups, .. . the loss of internal entropy on cyclization is small He offered this as an explanation for the apparent lack of a template effect in the cyclization. 

Benzylmercaptopropionyl-L-tyrosyl-L-phenyalanyl-L-glutaminyl-L-asparaginyl-S-benzyl-L-cysteinyl-L-prolyl-N-tosyl-D-arginyl glycinamide Sodium Ammonia Acetic acid... 

Solladie-Cavallo has recently reported a two-step asymmetric synthesis of dis-ubstituted N-tosylaziridines from (R,R,R,Ss)-(-)-sulfonium salt 2 (derived from Eliel s oxathiane see Section 1.2.1.1) and N-tosyl imines with use of phosphazine base (EtP2) to generate the ylide (Scheme 1.42) [67], Although the diastereoselectiv-ity was highly substrate-dependent, the enantioselectivities obtained were very high (98.7-99.9%). The chiral auxiliary, although used in stoichiometric quantities, could be isolated and reused, but the practicality and scope of this procedure is limited by the use of the strong - as well as expensive and sensitive - phospha-zene base. 

A range of electron-withdrawing groups on the nitrogen - N-P(0)Ph2, N-tosyl, and N-SES, for example - were tolerated. Imines derived from aromatic, heteroaromatic, unsaturated, and even aliphatic aldehydes and ketones were employed... 

Scheme 2.4 Aziridination of dienes with [(N-tosyl) iminojphenyliodinane 9.

Treatment of N-sulfmyl-as-aziridine-2-carboxylate 206 (Scheme 3.75) with LDA at -78 °C afforded 2H-azirine-2-carboxylate 207 in 47 % yield. The trans-aziridine 206 gave only a 9% yield of the desired product 207 [95]. Treatment of N-tosyl 2-substi-tuted aziridines 208 (Scheme 3.76) with LDA resulted in the formation of azirines 209 in 61-87% yield [95],... 

Metathesis of N-tosylated ene-amides and yne-amides has been less extensively investigated. An example of the RCM of ene-amides is a new indole synthesis developed by Nishida [79] metathesis precursor 96 (prepared by ruthenium-catalyzed isomerization of the corresponding allyl amide) is cy-clized to indole 97 in the presence of 56d (Eq. 13). 

Alkalimetallhydride reduzieren nicht. Man isoliert ausschlieBlich Olefine22. Bei der Umsetzung von Cyclo-hexanon-N-phenyl-N-tosyl-hydrazon mit Lithiumhydrid erhalt man die Azo-Stufe der Bamford-Stevens-Reaktion unter Bildung von Phenylazo-cyclohexen1. ... 

Oxazoborolidinone 8 is an example of catalyst supported on silica gel. It is prepared by immobilizing the N-tosyl-0-allyl-(S)-tyrosine with mercaptopropyl silica and treatment with BF3 and has been used to catalyze the Diels-Alder reaction of methacrolein with cyclopentadiene [17] (Equation 4.2). The cycloaddition occurs with good diastereoselectivity but with low enantioselec-tivity. 

An electrochemical method for amination has been reported by Shono et al. Derivatives of malonic esters containing an N-tosyl group were cyclized in high... 

N-Tosylated P-hydroxy alkylamines (which can be easily hydrolyzed to P-hydroxyamines" ) can be prepared " by treatment of alkenes with the trihydrate of Chloramine-T and a catalytic amount of OSO4. In some cases yields can be improved by the use of phase-transfer catalysis." The reaction has been carried out enantioselectively." In another procedure, certain P-hydroxy secondary alkylamines can be prepared by treatment of alkenes with the osmium compounds... 

The compound R2CuLi also adds to N-tosylated a,P-unsaturated amides Nagashima, H. Ozaki, N. Washiyama, M. Itoh, K. Tetrahedron Lett., 1985, 26, 657. 

Recently, enantioselective organo-catalytic procedures for the aza-Henry reaction have been disclosed. The presence of either an acidic or a basic function appears to be a requisite of the catalyst. In fact, the condensation of ni-tromethane with M-phosphinoyl arylimines 72 is catalyzed by the chiral urea 85 derived from (R,R)-l,2-diaminocyclohexane and gives the product (R)-74 with good yield and moderate enantioselectivity (Scheme 15) [50]. The N-phosphinoyl substituent is determinant, as the addition of nitromethane to the N-phenyl benzaldimine failed and the reaction of the N-tosyl ben-zaldimine gave the expected adduct with quantitative yield but almost no... 

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