Sulfonamide catalysts

Dosa and Fu reported the first catalytic enantioselective phenyl transfer reaction to ketones (equation 25)100. In the presence of 1.5 equivalents of MeOH, the chiral tertiary alcohol was produced in good yield and with high enantioselectivity. Walsh and workers recently reported the Ti(OE -i Vchiral dihydroxybis(sulfonamide) catalyst 34 system, whereby enones have been converted to enantioenriched allyl alcohols101. 

The bifunctional pyrrolidine sulfonamide catalyst, 38, having basic pyrrolidine nitrogen and Bronsted acidic sulfonamide function, mediates the addition of aldehydes to nitrostyrenes in high yield and selectivity (Scheme 2.47) [34]. Alkyl-substituted nitroolefins afford, however, product in low yield and in low selectivity. 

Jorgensen and co-workers employed chiral bis-sulfonamide catalyst 27, a proven ligand for metal-based asymmetric catalysis, for the Friedel-Crafts alkylations of N-methylindoles (24) using -substituted nitroolefins [52]. Using optimized conditions, 2 mol% 27 gave the desired indole alkylation products of substituted aryl and heteroaryl nitroolefins in moderate to high yields (20-91%) and moderate enantiopurities (13-63% ee Scheme 6.3). Aliphatic -substitution... 

Jorgensen and co-workers reported the asymmetric additions of a silyl ketene acetal to aldehydes (40) using the chiral bis-sulfonamide catalyst 27 [109]. Among the limited number of aldehydes examined, adducts were obtained in moderate to high yields (41-90%) and modest levels of ee (30-56% Table 6.44). The corresponding mono-sulfonamide catalyst was inactive under the reported conditions. 

Table 1 Alkylation of benzaldehyde in the presence of sulfonamide catalysts la-b...

This method is comparable to similar, catalytic Sim-mons-Smith-type methods employing the titanium TADDOL catalyst 20 (95 5 er) or the Ci-symmetric bis-sulfonamide catalyst 32 (93 7 er) for the cyclopropanation of the allylic alcohol 22 (eq 6). However, due to the preliminary nature of these earlier investigations, substrate scope and generality have not been extensively documented. All of the aforementioned methods are limited by their dependence on the allylic alcohol functionality. Only one method for Simmons-Smith-type cyclopropanation of other substrate classes has been developed. Use of a stoichiometric, chiral dioxaborolane [CAS 161344-85-0] additive allows for selective cyclopropanation of allylic ethers, homo-ally lie alcohols and allylic carbamates. ... 

The scope of the reaction was examined with a catalyst prepared from the benzene sulfonamide and DIBAL, because it was found that essentially the same induction could be obtained as with those obtained from tri-/so-butyl aluminum. Two years earlier the authors had reported that this Simmons-Smith reaction could also be catalyzed by the aluminum-free sulfonamide 132 (optimum with Ar = /7-NO2C6H4) the induction obtained is listed in the far right column of Table 8 [34]. It was proposed that a zinc complex of 132 is generated in-situ. Surprisingly, with the exception of the silyl-substituted allyl alcohol (the last entry in the table) [35], almost identical asymmetric induction obtained by use of the aluminum-containing and aluminum-free catalysts. The main advantage of the diazaaluminolidine catalyst is that it is apparently more soluble than the aluminum-free bis-sulfonamide catalyst, with the result that a tenfold increase in concentration (0.1 m) can be used this might explain the increased rate observed for the diazaaluminolidine catalyst. Finally, it has recently been reported that a catalyst formed from the Ci symmetrical sulfonamide 135 and DIBAL will induce the formation of 131 from cinnamyl alcohol in 68 % ee [36]. 

Griswold, K S, Horstmann, T E, Miller, S J, Acyl sulfonamide catalysts for glycosylation reactions with trichloroacetimidate donors, Synlett, 1923-1926, 2003. 

The comparative data in Scheme 11.11 highlights the superior catalytic efficiency of the sulfonamide 17 over the thiourea catalyst 13. Under the same reaction conditions (0.5 mmol of 15, 5 mmol of MeOH, 5 ml of Et20, and 1 mol% of catalyst), the sulfonamide catalyst 17 gave excellent enantioselectivity (95% ee) while the thiourea catalyst 13 gave only moderate ee (62%). The stereoselectivity of 13 can be increased to 88% ee only under highly dilute conditions, but at the expense of the reactivity [15]. 

Deprotonation of the N-H Bond in Sulfonamides Catalyst in an Anionic Ring-opening Polymerization. The addition of 5 mol % each of A-benzyl methanesulfonamide and KHMDS to a solution of 2-n-decyl-lV-mesylaziridine in DMF initiated a ring-opening polymerization providing a very low polydispersity polyamine polymer (eq 81). ... 

Scheme 2.10 Enantioselective Michael addition of ketones to nitroalkenes catalyzed by primary amine-sulfonamide catalysts 27a-b and by 9-epi amino cinchona alkaloid 28a.

Adolfsson and coworkers sereened a series of (S)-ATarenesulfonyl-2-aminomethylpyrrolidines and determined that sulfonamide 3d was the optimal catalyst for the direct asymmetric a-amination of aldehydes with diethyl azodicarbojq late (DEAD) as the amine source. The products were isolated as AT-amino oxazolidinones with moderate to good yields and enantioselectivities, after NaBH4 reduction and subsequent cyclisation. The advantage of this method was the low catalyst loading (1 mol%) of the sulfonamide catalyst (Scheme 9.42). 

The next progress in this field was obtained by the introduction of urea and thiourea types of catalysts (see Chapter 19), and especially quinine-derived sulfonamides (Figure 15.2). In addition to the excellent enantioselectivity, the efficacy of these catalysts is not temperature dependent (usually they are used at room temperature). Moreover, sulfonamide catalysts do not incline towards self-aggregation and therefore can be used under more concentrated conditions i.e. less solvent ). 

Ma et al. reported the asymmetric bromohydroiq lation of 2-aryl-2-propen-1-ols with N-bromosuccinimide (NBS). Regio- and enantioselectivity were achieved by using a boronate ester as a tether and quinine-derived sulfonamide catalysts 5. Products were obtained in up to 90% yield and with 96% ee (Scheme 15.35). 

In analogy with the above-mentioned amine-catalysed aldol reactions, our binaphthyl-based amino sulfonamide catalysts showed unique reactivity and selectivity in the asymmetric Mannich reaction of aldehydes. For instance, the Mannich reaction of propanal with an a-imino ester catalysed by (S)-3 gave the antr-Mannich adduct as a major diastereomer, while the syn-Mannich adduct was obtained in the proline-catalysed reaction first reported by the Barbas group (Scheme 17.8). ... 

A yyn-selective cross-aldol reaction of aldehydes with f-butyl glyoxylate and glyox-amide gives densely functionalized products in up to 99% ee, using a BINAP-derived axially chiral amino-sulfonamide catalyst. ... 

The same authors have designed novel chiral pyrrolidine-based amino sulfonamides, which were applied to promote a n -Mannich reactions of A/-PMP-protected a-imino esters with aldehydes, giving comparable results to those obtained with the binaphthyl-based amino sulfonamide catalyst. However, these novel pyrrolidine-based amino sulfonamides were found to be capable of promoting a //-Mannich reactions between A/-PMP-protected a-imino esters and a range of cyclic as well as acyclic ketones with excellent yields, enan-tioselectivities combined with moderate to high diastereoselectivities of up to 90% de (Scheme 3.13). 

A chiral bis-sulfonamide catalyst (35) was developed by Tonoi and Mikami and glyoxylates underwent hetero Diels-Alder reaction of Danishefsky s diene to give cyclohexenone derivatives with high ees (Scheme 2.78) [146]. 

Analogously to these examples, proline-derived peptide catalysts can also efficiently promote Michael addition reactions [97-99]. Prolinamide or prolyl sulfonamide catalysts are also effective for intramolecular Michael addition reactions [100-102]. Recently, Yang and Carter reported a short-cut strategy to construct an all-carbon substituted quaternary carbon stereogenic center on a cyclohexe-none framework via Robinson-type annulation using the 17-type catalyst (Scheme 1.4) [103]. 

After these reports, the same group extended the utility of this catalytic system to asymmetric Michael addition and aldol reactions (212, 213]. Sulfonamide catalysts such as 37-39 have also been developed for the same purpose [214-219]. The behavior of these catalysts, typically exemplified by enantioselec-tive Michael addition reactions of cyclohexanone with nitroolefins, is compiled in Scheme 1.15. 

Scheme 3.16 Primary amine-amides/sulfonamide catalysts.

A slightly different approach is represented by the use of the fluorous (S)-pyrrolidine sulfonamide catalysts 55 (Figure 24.18) [78]. The installation of the... 

In 2005, Jorgensen and Mikami independently reported the hetero-Diels-Alder reachon of Danishefsky s diene 114 with glyoxylates or glyoxals 118 using a class of chiral bis-sulfonamides catalyst 119a,b derived from 1,2-diphenyl-l,2-diamine... 

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