N-Sulfonyl

The isocyanide dichlorides are particularly attractive 1,1-bielectrophiles, and the N-sulfonyl derivative (138) underwent reaction with the iV-hydroxythioamide (137) to give the 1,3,5-oxathiazole derivative (139) (71AP763). Yields varied from 62% for R = Me and were slightly less for R = Ph (57%) and R = p-MeOC6H4 (50%). 

H-Azepine, 2-methyl-1-methoxycarbonyl-rearrangement, 7, 504 1 //-Azepine, 3-methyl-1 -methoxycarbonyl-cycloaddition reactions, 7, 520 IH-Azepine, 1-phenyl-synthesis, 7, 542 1 H-Azepine, N-phthalimido-formation, 7, 508 IH-Azepine, N-sulfonyl-UV spectra, 7, 501 1 H-Azepine, tetrahydromethylene-synthesis, 7, 540 IH-Azepine, N-p-tosyl-protonation, 7, 509 synthesis, 7, 537 3H-Azepine, 3-acyl-2-alkoxy-synthesis, 7, 542-543 3H-Azepine, 3-acyl-2-methoxy-rearrangements, 7, 505 3H-Azepine, 2-alkoxy-hydrolysis, 7, 510... 

From semiamidals, the correspondmg tnfluoromethyl substituted N-acyl mines [25, 28], 1,3-diambutadienes [27], N-sulfonyl mines [5, 29], N sulfinyl mines [30], and N-phosphoryl mines [31] can be obtamed in high yields on reaction with powerful dehydratmg realms like POC -pyndine or tnfluoroacetic anhydnde-pyndme [2, 5]... 

The total syntheses of fredericamycin 71 and camptothecin 72 made use of similar strategies. N-Sulfonyl-l-aza-1,3-butadienes in conjunction with electron rich dienophiles participated in the inverse electron demand Diels-Alder reaction to afford pyridines after treatment with base. 

Another chiral titanium reagent, 11, was developed by Corey et al. [17] (Scheme 1.24). The catalyst was prepared from chiral ris-N-sulfonyl-2-amino-l-indanol and titanium tetraisopropoxide with removal of 2-propanol, followed by treatment with one equivalent of SiCl4, to give the catalytically-active yellow solid. This catalyst is thought not to be a simple monomer, but rather an aggregated species, as suggested by NMR study. Catalyst 11 promotes the Diels-Alder reaction of a-bro-moacrolein with cyclopentadiene or isoprene. 

A series of chiral boron catalysts prepared from, e.g., N-sulfonyl a-amino acids has also been developed and used in a variety of cycloaddition reactions [18]. Corey et al. have applied the chiral (S)-tryptophan-derived oxazaborolidine-boron catalyst 11 and used it for the conversion of, e.g., benzaldehyde la to the cycloaddition product 3a by reaction with Danishefsky s diene 2a [18h]. This reaction la affords mainly the Mukaiyama aldol product 10, which, after isolation, was converted to 3a by treatment with TFA (Scheme 4.11). It was observed that no cycloaddition product was produced in the initial step, providing evidence for the two-step process. 

Addition, chloroform, to olefins to form 1,1,3 tnchloroalkanes, 46, 106 chlorosulfonyl isocyanate to isobutylene to give 0-isovaleiolactam-N-sulfonyl chloride, 46, SI cyclohexyl amine to silicon tetraiso-cyanate, 46, 69... 

Saito has recently reported high yields and enantioselectivities in aziridine synthesis through reactions between aryl- or vinyl-substituted N-sulfonyl imines and aryl bromides in the presence of base and mediated by a chiral sulfide 122 (Scheme 1.41) [66]. Aryl substituents with electron-withdrawing and -donating groups gave modest transxis selectivities (around 3 1) with high enantioselectiv-... 

Scheme 12.18 Synthesis of N-sulfonyl aziridines from 1,2-hydroxysulfonamides with DBU as a base.

Unactivated aziridines, such as 24, are not as reactive as their N-sulfonyl analogues. Nevertheless, in aqueous conditions they react with different nucleophiles, as Scheme 12.23 illustrates. Treatment with buffered azide at 50 °C gave 25 in 90% yield. Hydrazine proved potent even at room temperature and 26 was fonned in 95 % yield, while phenyltetrazole required heating at reflux in water. The resulting amines participated in dipolar cycloadditions with alkynes and condensations with P-diketones. 

O-Alkyl-7 und O-Aryl-hydroxylamine8 lassen sich mit Lithiumalanat in die Komponenten spalten bzw. re-duktivumlagern , O-Acyl-10bzw. N-Sulfonyl-hydroxylamine11 imerstenSchritt zum Hydroxylamin und Al-kohol bzw. Sulfonamid reduzieren. 

Keywords inverse electron-demand Diels-Alder reactions, N-sulfonyl-1-aza-1,3-butadiene... 

A related cyclization of N-sulfonyl-amino-alkenes and NBS gave the bromo-lactam, " and a dichloro-Af,7/-bisallylamide was converted to a dichloro-lactam with FeCl2. ... 

The azolide concept can be extended further to other TV-substituted azoles, such as N-sulfonyl- or TV-phosphorylazoles, for which an analogous gradation of reactivity is observed depending on the choice of the specific azole system. The reactions of these compounds are dealt with in Chapters 10 and 12, respectively. 

Similarly to the sydnonimines, unsubstituted oxatriazolium-5-amenates have been acylated with various acylating systems to N-acyl-, N-carbamoyl-, N-alkoxycarbonyl-and N-sulfonyl-derivatives [148] that represent chemically stable compounds (Scheme... 

An intermolecular reaction of N-sulfonyl-l,2-propadiene 250 with ethyl vinyl ether leading to tetrahydropyridine 254 was observed [131]. 

Fig. 11.9. Mechanisms and products of hydrolysis of aromatic N-sulfonyl imidates (11.66) as potential prodrugs of drugs containing sulfonamide or ester moieties [101] [102]...

The stability of these compounds is maximal at pH 4 - 6, and decreases very sharply at lower and higher pH values, and the mechanism and products of the reaction differed with pH. In the neutral range, hydrolysis yielded the aromatic sulfonamide and the ester, whereas, under acid catalysis in the low pH range, the products were the AT-acyl sulfonamide and an alcohol (R OH, Fig. 11.9). Of particular interest is that the tm values for hydrolysis of the N-sulfonyl imidates in 80% human plasma were 3-150 times lower than in buffer solution at identical pH and temperature. This was taken as evidence for enzymatic hydrolysis by human plasma hydrolases. Hydrolysis under these conditions yielded the sulfonamide and the ester in quantitative amounts. 

Syntheses of this class of compounds usually involve 1,2,5-thiadiazepine ring 333 (Figure 6) which is stable in the S-oxidized form and structurally represents cyclic pyrrole N-sulfonyl derivatives. Most of the synthetic strategies include formation of an S-Npyrroie bond in the early stages. A final cyclization step typically includes (i) intramolecular cyclization by creation of an N-X bond from a suitable pyrrole precursor or (ii) a 6 + 1 type cyclization that involves dielectrophilic species to form linker X and utilizes the nucleophilicity of the phenyl amino group and of the pyrrole ring at C2. Intramolecular processes with the formation... 

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