Gold(i)-catalyzed cycloisomerization of alkynyl hydroxyallyl tosylamides to 4-oxa-6-azatricyclo[3.3.0.02,8]octanes

Abstract

Reaction of alkyne allyl alcohols tethered with N-(p-tolylsulfonamide) in the presence of a cationic gold(I) catalyst gave new cycloisomerization products, 4-oxa-6-azatricyclo[3.3.0.0(2,8)]octanes.

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

“…As an example, the synthesis of 4-oxa-6-azatricyclo[3.3.0.0 2,8 ]octanes 285 was reported by a complex gold-catalyzed cycloisomerization of alkynyl hydroxyallyl tosylamides 282 in the presence of Ph 3 PAuCl and AgSbF 6 (Scheme 88 ). 257 …”

Keteniminium Induced Dienone‐Phenol Rearrangement and Intramolecular 6‐endo‐dig Cyclization Cascade of Yne‐Dienone

“…Interestingly, the catalyst combination of PPh 3 AuCl (5.0 mol-%) or JohnPhosAuCl (5.0 mol-%) with AgNTf 2 (10 mol-%) in CHCl 3 (0.05 M) at 60 °C for 12 h delivered 3a in 20 % and 78 % yield, respectively with better Z/E selectivity (entries 5 and 6). To examine the effect of counter anion, various silver salts, for example: AgSbF 6 , AgBF 4 , and AgOTf in combination with JohnPhosAuCl (5.0 mol-%) were tested (entries [7][8][9]; in all such cases, 3a was formed only in a trace amount. The reaction didn't proceed in the absence of either AgNTf 2 or JohnPhosAuCl (entries 10 and 11).…”

“…[1 -4] In one hand, the π-acidic and carbophilic Au(I)-catalysts are being successfully employed for various cascade cyclization and cycloisomerization of unsaturated systems for the construction of polyfused carbo-and heterocycles. [5][6][7][8][9] While in other hand, the Au-catalyzed hydrofunctionalization and difunctionalization of unsaturated alkynes provides access to highly functionalized olefin derivatives. [10 -12] In this context, Au-catalyzed hydrophenoxylation of phenol with alkyne leading directly to aryl-vinyl ethers is well-studied (Scheme 1,a), [13 -18] by contrast, the identical process with ynamide is so far less explored.…”

Gold-Catalyzed Synthesis of Small Rings

“…The same group later described the formal [4 + 2] cycloaddition of N -tethered enynes with a 1,3-diene unit 384 and prepared related 4-oxa-6-azatricyclo[3.3.0.0 2,8 ]octanes by cycloisomerization of N -tethered internal 1,6-enynes bearing an allylic alcohol. 385 O -Tethered 1,6-enynes with an enol ether as the alkene component delivered similarly complex cage structures. 386 …”

“…The same group later described the formal [4 + 2] cycloaddition of N-tethered enynes with a 1,3-diene unit 384 and prepared related 4-oxa-6azatricyclo[3.3.0.0 2,8 ]octanes by cycloisomerization of Ntethered internal 1,6-enynes bearing an allylic alcohol. 385 O-Tethered 1,6-enynes with an enol ether as the alkene component delivered similarly complex cage structures. 386 The intermolecular version of these reactions was developed trapping with external alkenes two different cyclopropyl gold carbene intermediates (116 and 117) generated from 1,6enynes (Scheme 34).…”