Dendralenes are simple alkenes with cross‐conjugated double bonds that are frequently synthesized due to being potentially valuable building blocks for the synthesis of more complex structures. The synthetic approaches to dendralenes are based on the cross‐coupling reactions of electrophilic and nucleophilic synthons derived from geminally substituted ethylene. Our novel methodology for the synthesis of only terminally substituted [3]‐ and [4]dendralenes, as well as 2,3‐disubstituted buta‐1,3‐dienes, involves the preparation of 1,2‐disubstituted cyclobutenes from readily available 2‐bromocyclobutanone and the subsequent thermal ring‐opening reactions.
The first high-yielding route to arylated 2H-pyrroles was developed. The methodology utilizes 2,5-disubstituted pyrroles that are metalated, and the aryl substituents are introduced by a palladium-catalyzed cross-coupling reaction. The prepared pyrroles can be rearranged to 2,3,5-trisubstituted pyrroles under acidic conditions. Attempts to convert the 2,3,5-trisubstituted pyrroles to 2,3,4,5-tetrasubstituted pyrroles by the dearomatization rearrangement strategy were unsuccessful.
A new method for the stereoselective cross‐coupling reaction of arylzinc chlorides with trisubstituted enol phosphates is described. The developed method requires aluminum chloride as a promoter, and the reaction conditions tolerate various functional groups. The observed reactivity pattern of trisubstituted enol phosphates was used for the stereoselective preparation of tamoxifen and its analogues.
Unprecedented formal transition-metal-catalyzed phosphole C− H functionalization is described in this paper. Pentasubstituted phospholes were prepared via the copper-catalyzed reaction of 1,3,4-trisubstituted phosphole with aryl iodides or bromides under distinct conditions. The developed methodology is able to accommodate a wide variety of substituents, including aryl, heteroaryl, and alkenyl.
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