Intramolecular with sulfamides

The sulfamate ester variant of this chemistry has already been shown to be a very powerful protocol for the syntheses of 1,3-amino alcohols and related /3-amino acids (Equation (90)), as well as iminium ion equivalents (Equation (91)). The further showcases of this chemistry are the total syntheses of the bromopyrrole alkaloids, manzacidins A and C (Scheme 13).234 The cyclic sulfamidate 129 was obtained diastereospecifically from sulfamate 128 using intramolecular rhodium-catalyzed G-H insertion. It was then found to react with sodium azide in NfN-dimethylformamide at room temperature after introduction of the Boc-activating group to afford the 1,3-diamino precursor 130 in 78% yield over 3 steps. Four subsequent manipulations afford the target structure 131. 

Unsymmetrical 1,2-diarylethane diamines, the formal cross-coupling products of two different imines, are produced by intramolecular reactions of dibenzylidene sulfamides with a combination of zinc and Me3SiCl in DME or Sml2 in THF (Equation (57)). 

In addition to epoxides, three-membered nitrogen heterocycles, aziridines, can be obtained by means of catalytic asymmetric aziridinations (Eq. 30). To this aim, chiral ruthenium(salen) complexes 67 [56] and 68 [57] were useful (Fig. 1). The former phosphine complexes 67 gave the aziridine from two cy-cloalkenes with 19-83% ee [56]. On the other hand, terminal alkenes selectively underwent aziridination in the presence of the latter carbonyl complex 68 with 87-95% ee [57]. In these examples, N-tosyliminophenyliodinane or N-tosyl azide were used as nitrene sources. Quite recently, catalytic intramolecular ami-dation of saturated C-H bonds was achieved by the use of a ruthenium(por-phyrin) complex (Eq. 31) [58]. In the presence of the ruthenium catalyst and 2 equiv iodosobenzene diacetate, sulfamate esters 69 were converted into cyclic sulfamidates 70 in moderate-to-good yields. 

Diamination of alkenes can also be achieved intramolecularly through the nickel-catalyzed oxidation reaction, affording a wide-range of different cyclic sulfamides <07AG(E)7125>. The cyclization of sulfamide 223 proceeds in the presence of NiCU or Ni(acac)2 (10 mol%) and PhI(OAc)2 with complete selectivity, and no products other than cyclic sulfamides are observed. An initial involvement of aminometalation generates a cyclic intermediate 224. The subsequent oxidative C-N bond formation, presumably via a Ni(III) intermediate from oxidation with PhI(OAc)2, yields the bicyclic sulfamide 225. The reaction scope is well extended to the formation of spiro-cyclic sulfamides, tricyclic sulfamides and chiral substrates... 

C-H Amination. A number of amine-based starting materials will react with PhI(OAc)2 and a transition metal catalyst to promote selective C-H bond amination. Intramolecular oxidation of substrates such as carbamates, ureas, sulfamates, sulfonamides, and sulfamides affords the corresponding heterocycles in high yields and, in many cases, with excellent diastereocontrol (eqs 60 and 61). Insertion into optically active 3° C-H centers is reported to be stereospecific (eq 62). Chiral Ru, Mn, and Rh catalysts have all been utilized for asymmetric C-H amination, though product enantiomeric induction is variable. Many of the heterocyclic structures furnished from these reactions function as versatile precursors to 1,2- and 1,3-amine derivatives. 

Scheme 6 exemplifies the first path. Intramolecular cyclization of sulfonamides 1 is caused by action of a base, thus resulting in the formation of nitroaromatics fused with five- or six-membered heterocycles [22-24]. It should be emphasized that in some cases the formation of isomeric products can be observed due to a nucleophilic attack at the para-position relative to the nitro group. Also it is worth noting that the cyclic sulfamides 2 and 3 can be used as precursors to obtain some other N-heterocyclic compounds, such as isoindoles 4 [25] or 1,2,3,4-tetrahydroquinolines 5 [24] (Scheme 6). 

In 2001, Du Bois and co-workers developed the intramolecular amination of diverse C—H bonds, including aliphatic ones, by employing the commercially available Rh-catalyst [Rh2(OAc)4] and oxidant PhI(OAc)2. Inspired by this work, Muller and co-workers realized intra- and intermolecular amidation reactions by in situ formed nitrene species. Employing the chiral dirhodium Rh2(S-NTTL)4 developed by their group, cyclic sulfamidates 104 were synthesized in good yields and stereocontrol with sulfamates 103 and PhI(OAc)2 as the nitrene precursors (Scheme 1.37). Subsequently, they... 

Additionally, the use of Rh2(esp)2 has extended the intramolecular C(sp )—H amination reaction to other types of nitrene precursors (Scheme 11). Appfication of the reaction conditions to ureas and guanidines, thus, gives access to valuable building blocks for the synthesis of drug candidates or natural products.A diverse range of 1,3- and 1,2-diamines is, also, easily accessible, respectively from sulfamides and hydroxylamine-derived sulfamates.In each case, 1—2 mol% of catalyst 3 is sufficient to isolate the expected cycfic products with excellent yields of up to 99%. 

Scheme 30 Diastereocontrol in intramolecular C(sp )-H amination reactions with sulfamates and sulfamides.

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