Olefin with sulfonamides

Oxidative aminations of olefins with sulfonamides also appear to occur by insertions of alkenes into Pd-N bonds in some cases. An example of the use of stereochemistry to probe for syn or anti addition of palladium and nitrogen aaoss an alkene during oxidative amination is shown in Equation 9.89b. The stereochemistry of the alkene unit indicates that the reactions occur by insertions of olefins into Pd-N bonds. As shown in Equation 9.89b, frie E-olefin containing a pendant sulfonamide would form the E-product if syn addition of the palladium and sulfonamido group occurs during the catalytic process, but it would form the Z-product if anti addition occurred. The product from syn addition is formed, and such syn stereochemistry is consistent with migratory insertion of the olefin into a palladium-sulfonamido intermediate. ... 

Flowever, Mansuy el al. reported that treatment of olefins with [A-(p-toluenesulfonyl)imino]-phenyliodinane, PhI=NTs, in the presence of a Mn or Fe porphyrin, provided the corresponding aziridine or allylic sulfonamide, depending on the substrate and the catalyst used (Scheme 33).145-147 The reaction has been considered to proceed through a metal-A-toluenesulfonylnitrenoid species. Similarly to epoxidation via the oxo-Mn species, this aziridination is nonstereospecific, and the participation of a radical intermediate has been suggested.146... 

The use of metal-catalyzed aziridination methods with chiral ligands has also been reported. The copper-based system paired with ligand 56 provides the expected cinnamyl aziridine in good yield and excellent ee <06MI4568>. It is interesting to note that the /-butyl ester is obtained with 99% ee while the smaller methyl ester is obtained in only 88% ee. The binaphthyl ruthenium catalyst 57 has been found to aziridinate a number of olefins with moderate enantioselectivity <06TL1571>. Both p-nitrophenyl (Ns) and trimethylsilyloxy (SES) sulfonamides work well with this catalytic system. As is usually seen, the aziridination of aliphatic olefins proceeds in only 32% yield and 56% ee. 

With this revision in our original plans, both alkenes and allenes were found to undergo efficient cycloadditions to produce cyclooctenone products in a new [6+2] cycloaddition process. This novel cycloaddition has been shown to proceed efficiently with alkenes tethered with sulfonamide, ether, or geminal diester Hnkers (Tab. 13.15, see page 294). Isomerization of the olefin, a potential competing reaction in this process, is not observed. Methyl substitution of either alkene in the substrate is well tolerated, resulting in the facile construction of quaternary centers. Of mechanistic importance, in some cases cycloheptene byproducts were isolated from [6+2] cycloaddition reactions in addition to the expected cyclooctenone products (that is, entries 3 and 4). 

The intermolecular addition of carbamates to 1,3-dienes (equation 147) under mild conditions has been described as well. The hydrothiolation of 1,3-dienes has also been reported. " Other related conjugate additions can be performed over methylenecyclopropanes (equation 148) with sulfonamides and the resulting product cyclizes by a second hydroamination of an olefin, finally yielding cyclic sulfonamides. This behavior is reproduced in a similar reaction for the ring opening of vinylcyclopropanes with sulfonamides. One more example in this group of reactions is the synthesis of dUiydrobenzofurans from aryl-allyl ethers. ... 

The intramolecular reaction of vinyl-cyclopropanes tethered to alkenes 206 yielding fused bicyclic products 207 has also been applied to the [5-f2-l-l] cycloaddition (Scheme 92) (164). However, in this case, a low partial pressure of CO was found to be effective. Substrates with sulfonamides, ethers, and germinal diesters tethers were effective in the cycloaddition. In addition, substitutions on either the olefin component or the VCP component were also tolerated yielding 5-8 fused ring products with high diastereoselectivity. The ElZ olefin geometry... 

A related example disclosed recently by McNulty et al. is a one-pot Wittig reaction of aldehydes with phosphonium salts in the presence of 10 mol% of morpholine, L-proline or p-toluenesulfonamide and 2.0 equiv. of NaHCOs (Scheme 55) [227]. This reaction gives high E selectivity. A rapid and reversible condensation of the aldehyde with the amine (derivative) catalyst has been proposed to form an iminium or an imine intermediate that is subjected to olefination with the in situ generated phosphonium ylides, though a base-catalyzed pathway is not ruled out. It has been confirmed that an N-sulfonyl imine can be formed quantitatively from the corresponding aldehyde and sulfonamide under the reaction conditions. 

General Reaction Chemistry of Sulfonic Acids. Sulfonic acids may be used to produce sulfonic acid esters, which are derived from epoxides, olefins, alkynes, aHenes, and ketenes, as shown in Figure 1 (10). Sulfonic acids may be converted to sulfonamides via reaction with an amine in the presence of phosphoms oxychloride [10025-87-3] POCl (H)- Because sulfonic acids are generally not converted directiy to sulfonamides, the reaction most likely involves a sulfonyl chloride intermediate. Phosphoms pentachlotide [10026-13-8] and phosphoms pentabromide [7789-69-7] can be used to convert sulfonic acids to the corresponding sulfonyl haUdes (12,13). The conversion may also be accompHshed by continuous electrolysis of thiols or disulfides in the presence of aqueous HCl [7647-01-0] (14) or by direct sulfonation with chlorosulfuric acid. Sulfonyl fluorides are typically prepared by direct sulfonation with fluorosulfutic acid [7789-21-17, or by reaction of the sulfonic acid or sulfonate with fluorosulfutic acid. Halogenation of sulfonic acids, which avoids production of a sulfonyl haUde, can be achieved under oxidative halogenation conditions (15). 

Sulfonamides. A/-Halo-A/-alkylsulfonamides, RS02NR X, are relatively stable distillable Hquids. Under the influence of uvlight they form 1 1 adducts with olefins (67,100). Ai-/-Butyl derivatives rearrange forming precursors to cyclopropanes and sultams. A/-Halo-A/-sodioalk5lsulfonamidates, RS02NClNa, have been less extensively studied than their aromatic counterparts (70). The stabiHty of these compounds approaches that of the aromatic sulfonamides (80). The dodecyl compound exhibits properties of both a disinfectant and a surfactant. 

It has also been shown that dimethylsilyl enolates can be activated by diisopropylamine and water and exhibit a high reactivity toward iV-tosyl imines to give Mannich-type reaction products in the absence of a Fewis acid or a Bronsted acid.51 For example, the reaction of [(1-cyclohexen-l-yl)oxy]dimethylsilane with 4-methyl-A -(phenylmethylene)benzene sulfonamide gave re/-4-methyl-N- (f )-[(15)-(2-oxocyclohexyl)phenyl-methyl] benzenesulfonamide (anti-isomer) in 91% yield stereoselectively (99 1 anti syn) (Eq. 11.30). On the other hand, Fi and co-workers reported a ruthenium-catalyzed tandem olefin migration/aldol and Mannich-type reactions by reacting allyl alcohol and imine in protic solvents.52... 

Non-metal catalyzed aziridinations have also been reported. These methods are often more broadly applicable than the metal-catalyzed methods. The use of iV-methylpyrrolidine-2-one hydrotribromide (MPHT) and chloramine-T is an effective route for the synthesis of iV-tosyl aziridines <06MI16>. The aziridination of olefins using i-BuOI and sulfonamides appears to be a general method for aziridination <06CC3337>. The i-BuOI is prepared in situ from t-BuOCl and Nal. This is a broadly applicable method in that a wide variety of sulfonamides (tosyl, nosyl, SES) can be used with roughly equivalent yields. 

Intramolecular aziridinations of the olefinic sulfonamides 297, by means of the iminoiodane derivatives 298, have recently been demonstrated (Scheme 85) (OOOL2327). Ring-opening reactions of the bi- and tricyclic sultams 299, thus obtained, with selected nucleophiles were explored and provide access to functionalized cyclic sulfonamides. 

The easiest reactions are those in which the nucleophile is the gold-activated species. Examples of this are Au(I)-catalyzed carbene and nitrene transfers (equations 142 and 143) that convert olefins into cyclopropanes or aziridines, respectively. In the carbene transfer, ethyl diazoacetate is the source of carbene and the active NHC-gold cationic catalyst is generated by chloride abstraction with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate NaBAT4. The cyclopropanation is competitive with other carbene insertions with active C H or N H bonds present in the substrate. For the aziridinations of olefins, nitrene formation is accomplished by the oxidation of sulfonamides with PhI(OAc)2 and the catalyst of choice is a gold-(I) triflate with a terpyridine ligand. 

Hydroamination of olefins is also possible with gold catalysts. In this reaction, the attack comes Ifom a nitrogen nucleophile as a carbamate,a urea, an amide, or a sulfonamide. In the latter case, the reaction can be carried out intermolecularly. While the carbamates, ureas, and amides give only products of intramolecular anunations, the sulfonamides can perform the intermolecular addition. Only the addition of ureas (equation 146) takes place at room temperature, and in the rest of the additions heating is required. The catalysts of choice in all these reactions are cationic gold(I)-species stabilized by phosphines or NHC ligands. The reaction times have been reduced by the use of microwave irradiation. The mechanism of the hydroamination reaction has been studied in detail theoretically. ... 

An asymmetric variant of this kind of allylic amination, based on their phenylcyclohexanol-derived chiral N-sulfinyl carbamates, was developed by Whitesell et al. (see also Sect. 3.2) (Scheme 34) [85]. After the asymmetric ene reaction with Z-configured olefins (not shown) had occurred, nearly di-astereomerically pure sulfinamides 127 were obtained which were found to be prone to epimerization. Their rapid conversion via O silylation and [2,3]-a rearrangement dehvered the carbamoylated allyhc amines 128 with around 7 1 diastereoselectivity as crystalline compounds that can be recrystallized to enhance their isomeric purity to 95 5. Obviously the imiform absolute configuration at Cl in the ene products 127 was difficult to transfer completely due to the already mentioned ease of epimerization. Unhke the sulfonamides of Delerit (Scheme 33) [84], the carbonyl moiety can easily be cleaved by base treatment. 

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