Silver-Catalyzed 1,3-Acyloxy Migration/Diels–Alder Reaction of 1,9-Dien-4-yne Esters to Partially Hydrogenated Isoquinolines

Abstract

A synthetic method to prepare partially hydrogenated isoquinolines efficiently from silver-mediated [3,3]-sigmatropic rearrangement/Diels-Alder reaction of 1,9-dien-4-yne esters is described. The reactions were shown to be robust with a wide variety of substitution patterns tolerated to provide the corresponding nitrogen-containing heterocyclic products in good to excellent yields. This includes examples containing a bridgehead sp quaternary carbon center as well as the cycloisomerization of one substrate to give the corresponding bicyclic adduct in excellent yield at the gram scale.

Rhodium(I)‐Catalyzed Three‐Component [4+2+1] Cycloaddition of Two Vinylallenes and CO

“…We hypothesized that if a bulky group R 1 such as t Bu was introduced, the corresponding substrates 1 p – 1 r could have a cis configuration between rhodium and the linker moiety, which then has the possibility to give 6/7 ring product (Scheme 4). To our surprise, we found that 1 p was converted to the [4+2] cycloaddition product 5 in 81 % yield, and the desired 6/7 ring compound was not obtained [14] . Yne‐vinylallene substrates 1 q and 1 r also failed to give [4+2+1] products.…”

“…To our surprise, we found that 1p was converted to the [4+ +2] cycloaddition product 5 in 81 %y ield, and the desired 6/7 ring compound was not obtained. [14] Yne-vinylallene substrates 1q and 1r also failed to give [4+ +2+ +1] products. Theser esults imply that, though the right configuration of oxi- Table 2.…”

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…The robust reactions were applied on broad range of substrates bearing EDG and EWG functional groups in obtaining the desired products in good to excellent yields (Scheme 14). [52] Yang et al have developed an Ag-catalyzed rearrangement of N-sulfonyl-4-(2-(ethynyl)aryl)-1,2,3-triazoles 33 through silver carbenoid intermediate and subsequent annulation leading to the formation of isoquinolines 35. The present protocol rely on ring opening, N 2 extrusion, silver carbenoid formation followed by nucleophilic addition and subsequent complex annulation.…”

“…The robust reactions were applied on broad range of substrates bearing EDG and EWG functional groups in obtaining the desired products in good to excellent yields (Scheme 14). [52] …”

Product Divergence in Coinage-Metal-Catalyzed Reactions of π-Rich Compounds

“…In a subsequent study, the same starting material was subjected to JohnPhosAgSbF 6 , formed in situ, which furnished hexahydroisoquinolines 42 (Scheme 9, route b). 16 It was proposed that the less reactive silver(I) catalyst was unable to initiate Nazarov cyclization and this resulted in the preferential formation of vinyl allene 41. An ensuing intramolecular DA reaction of the allene motif with the terminal alkene unit in the intermediate afforded the hexahydroisoquinolines 42 in yields of 34-99%.…”