Regiocontrolled synthesis of enantioenriched 2-substituted dehydropiperidines by stereospecific allyl–allyl cross-coupling of a chiral allylic boronate

Abstract

The palladium-catalyzed cross-coupling of an optically enriched dehydropiperidinyl boronate with cinnamyl carbonates was optimized to minimize stereochemical erosion. Although the coupling of two unsymmetrical allyl fragments may generate four possible...

Recent development of allyl–allyl cross-coupling and its application in natural product synthesis

“…In 2022, Hall et al synthesized 44 optically enriched 2-allylated 3,4-dehydropiperidines in good yields using a palladium-catalyzed stereospecific allyl–allyl cross-coupling reaction between an enantioenriched piperidinyl allylic boronate and allylic carbonates (Scheme 10). The coupling reaction was carried out in the presence of 5 mol% Pd(OAc) 2 and 10 mol% ( p -CF 3 C 6 H 4 ) 3 P as the ligand for 16 h to afford up to 76% product yield.…”

Regioselectivity Switch Towards the Development of Innovative Diels‐Alder Cycloaddition and Productive Applications in Organic Synthesis

“…Regioselective and stereospecific coupling protocols are the most fascinating subjects among organic synthesis. [83,84] Hall and co-workers in 2014, achieved a regio-and stereospecific Suzuki-Miyaura cross-coupling of pyran allylboronates with aryl and alkenyl organobromides as part of their efforts to establish innovative methods in this field. [85] The enantiomerically enriched allylboronates were easily accessed via variety of pathways (general pathway shown in Scheme 7a).…”

Rh-catalyzed regio-switchable cross-coupling of gem-difluorinated cyclopropanes with allylboronates to structurally diverse fluorinated dienes

“…Allyl–allyl cross-coupling reactions catalyzed by a transition-metal complex play an important role in organic synthesis, not only because they constitute a robust and efficient method for the construction of C(sp 3 )–C(sp 3 ) bonds, but also because the two olefin moieties in the products enable diversified downstream transformations. 1–4 Typically, allyl–allyl cross-coupling reactions proceed between allylic electrophiles and allylmetal reagents, and the two allyl moieties are connected together at the terminal site of the allyl fragments through reductive elimination, resulting in the formation of different types of 1,5-dienes via linear 2 or branched 3,4 selectivity (Scheme 1a). Furthermore, the introduction of chiral ligands in allyl–allyl cross-coupling reactions, 4 mainly contributed by Morken and coworkers, 4 a –4 f allows the generation of enantioenriched 1,5-diene structures, which further enhances the importance of this methodology in synthetic chemistry.…”

“…13 In the aspect of allyl–allyl cross-coupling reactions, the control of linear and branched selectivity has been well-developed, in which the C–C bond was formed at the terminal site of the allyl moiety. 1–4,12 While there are great advancements in the linear/branched control of allyl–allyl cross-coupling reactions, a strategy that can form a bond connection at the internal site of an allyl moiety to achieve terminal/internal-switchable regioselectivity remains elusive. 14 As continuous research interest on the development of new reactivity of gem -difluorinated small rings, 10,15 we envisioned that this challenge can be potentially addressed by the use of gem -difluorinated cyclopropanes as fluoroallyl surrogates under rhodium catalysis.…”