Heck cascade

Brase reported an intramolecular asymmetric Heck-intermolecular Heck cascade reaction of l,3-bis(enolnonaflates) 131 to the highly congested bicyclic compound 132 [122] (Scheme 5). Although the level of asymmetric induction is low (up to 52% ee), this result shows that the concept of two leaving groups in the desymmetrization reaction can be applied. 

BujSnH Stille-Heck cascade on enynes Hydrostiinnylation [107]... 

Scheme 3-23 An inter-intramolecular Suzuki-Heck cascade [174],...

Various types of domino reactions have been reported in the recent past. The sequential or cascade combination of an olefin metathesis with an intramolecular Heck reaction provides access to various bicycUc spirocyclic ring systems in good yields. Recently, a one-pot metathesis-Heck cascade was employed in the constraction of various ring systems (Scheme 57). " ... 

Alternatively, tetrahydroanthracene 85 was also obtained directly from symmetrical ditriflate 86 by a Suzuki cross-coupling/asymmetric Mizoroki-Heck cascade reaction. In this case, reaction of ditriflate 86 with alkylborane 82, Pd(OAc)2, (S)-BINAP and K2CO3 in THF at 60 °C directly gave product 85 in high enantiopurity, albeit in 20% yield. Although the yield for this one-pot conversion was poor, this transformation represents a novel application of the asymmetric Mizoroki-Heck cyclization and remains the only reported example of cascade Suzuki cross-coupling/asymmetric Mizoroki-Heck cyclization. A series of additional synthetic transformations was required to convert 85 to pentacyclic intermediate 87, which had earlier been converted by Harada et al. [53] to halenaquinone (88) and halenaquinol (89). 

Allyl complexes as intermediates The Stille-Heck cascade on enynes... 

Scheme 8.27 An inter-intermolecular two pot Stille-Heck cascade for the assembly of tri- and tetracyclic systems [323].

SCHEME 21.15. Wacker-Heck cascade for the synthesis of a-tocopherol. 

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