Transition Metal-Mediated Intramolecular [2+2+2] Cycloisomerizations of Cyclic Triynes and Enediynes

Abstract

[reaction: see text] Nitrogen-containing 15-membered triacetylenic macrocycles known as 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triynes (1) and enediynic macrocycles called 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3-ene-8,13-diynes (4 and 5) were satisfactorily prepared. [2+2+2] cycloisomerization processes catalyzed by transition metals were tested in the above-mentioned macrocycles. Readily available and familiar cyclotrimerization precatalysts were examined for efficiency. Among them, the RhCl(CO)(PPh(3))(2) complex was found to catalyze the cycloisomerization reaction giving the desired cycloadducts in high yields.

Rhodium(I)‐Catalysed Intramolecular [2+2+2] Cyclotrimerisations of 15‐, 20‐ and 25‐Membered Azamacrocycles: Experimental and Theoretical Mechanistic Studies

“…To introduce an arylic unit that was different to the other three and to prepare 3 b, an alternative synthetic route was used (see Scheme 2). Condensation between dichloro derivative 11 b, [8] which introduces the differential aryl unit, and trisulfonamide 12 a [6] afforded a 96 % yield of macrocycle 3 b. Reaction of 12 b [6] with 11 b [8] gave macrocycle 3 c containing four units of 2,4,6-triisopropylphenyl.…”

“…[ [5][6][7][8] When 20-membered macrocycles 3 a-c, heated under reflux in toluene, were treated with [RhCl-…”

“…Partially intramolecular approaches or fully intramolecular cycloaddition processes represent efficient entries into various multiple-fused ring compounds. Over the last few years, we have developed an efficient rhodium(I)-catalysed [2+2+2] cyclotrimerisation process of 15-, 16-and 17-membered triynic and enediynic azamacrocycles of type 1 (to give compounds 2) and have described the first examples in the literature of completed closed systems [5][6][7][8] (Scheme 1). To broad-…”

Functionalisation of Macroheterocycles with Preserving and Changing Their Sizes

“…Thus, nitrogen-containing 15-membered triacetylene (272), enediyne (273) the reaction proceeds stereospecifically in case of enediyne macrocycles (Scheme 60). [133,134] Other products (278) and (279) have been obtained in thermally induced [2+2+2] cycloisomerisation, though in moderate yields but high stereoselectivities: only isomers in cys-location of hydrogen atoms in unsaturated azacyclopentyl rings have been formed (Scheme 61). [133,134] The [2+2] cycloaddition reaction of stilbenes during their UV irradiation is one of the most efficient methods of synthesis of cyclobutane-substituted derivatives.…”

“…[133,134] Other products (278) and (279) have been obtained in thermally induced [2+2+2] cycloisomerisation, though in moderate yields but high stereoselectivities: only isomers in cys-location of hydrogen atoms in unsaturated azacyclopentyl rings have been formed (Scheme 61). [133,134] The [2+2] cycloaddition reaction of stilbenes during their UV irradiation is one of the most efficient methods of synthesis of cyclobutane-substituted derivatives. Thus, UV irradiation of both cis-(280) and trans-(281) macrolide stilbenes obtained from commercially available cis-(282) or trans-(283) stilbene-4,4'-dicarbolylic acid dimethyl ester led to the formation of the sole product (287) by their transfer in two steps to dibromides (284) and (285) followed by cyclization with triazinone (286) in the presence of NaOH in THF and the removal of protective groups under the action of diethanolamine.…”