Phosphine‐Initiated Cascade Annulation of β′‐Acetoxy Allenoate and p‐Quinols: Access to Ring Fused Hexahydroindeno Furan Derivatives

Abstract

A highly diastereoselective cascade annulation process of p‐quinols with β′‐acetoxy allenoate catalyzed by phosphine has been developed, which comes up with highly functionalized multiple ring‐fused hexahydroindeno furan derivatives in synthetically useful yields and creates three consecutive stereogenic carbon centers only in a one‐step manner. The salient features of this phosphine‐catalyzed cyclization include the use of p‐quinol's three active sites in this cascade reaction, wide substrate scope, excellent functional group tolerance, mild reaction conditions, asymmetric version, good yields, ease of scale‐up to gram scale, and further transformations.magnified image

Site-selective and stereoselective transformations on p-quinols & p-quinamines

“…Afterwards, it further underwent intramolecular conjugate addition to give bicyclic intermediate 34.D followed by intramolecular cyclization affording the fused hexahydroindeno furan 34.3 along with the regenerated phosphine catalyst (Scheme 34). 30 Since p-quinols have both electrophilic and nucleophilic sites, they can easily undergo self dimerizations and trimerizations under suitable conditions to produce highly complex products with excellent diastereoselectivity. In 2018, Duarte, Lawrence and co-workers demonstrated the sequential oxa-Michael/Diels-Alder/oxa-Michael addition of p-quinols 35.1 in the presence of a pyrrolidine catalyst.…”

“…Afterwards, it further underwent intramolecular conjugate addition to give bicyclic intermediate 34.D followed by intramolecular cyclization affording the fused hexahydroindeno furan 34.3 along with the regenerated phosphine catalyst (Scheme 34). 30…”

Molecular Complexity from Aromatics: Recent Advances in the Chemistry of paraQuinol and Masked para‐Quinone Monoketal

“…The mechanism was thought to follow on the same line as mentioned by Sasai, [101] but here in the final step electrophile was attacked at a‐position of para ‐quinol and delivering one more ring (Scheme 35). [98] …”

Synthesis and Antimicrobial Activity of the Pathogenic E. coli Strains of p-Quinols: Additive Effects of Copper-Catalyzed Addition of Aryl Boronic Acid to Benzoquinones

“…p -Quinol skeletons are frequently found in many bioactive natural products [ 1 , 2 , 3 , 4 ], and they also serve as useful synthetic building blocks [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ] ( Scheme 1 ). Moreover, p -quinol glycosides are known from analgesic activities [ 27 ].…”