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A One‐Pot Sequence of Stille and Heck Couplings: Synthesis of Various 1,3,5‐Hexatrienes and Their Subsequent 6π‐Electrocyclizations
Author(s) -
von Zezschwitz Paultheo,
Petry Frauke,
de Meijere Armin
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010917)7:18<4035::aid-chem4035>3.0.co;2-p
Subject(s) - stille reaction , trifluoromethanesulfonate , yield (engineering) , catalysis , chemistry , styrene , heck reaction , sequence (biology) , palladium , bicyclic molecule , stereochemistry , combinatorial chemistry , organic chemistry , copolymer , materials science , polymer , biochemistry , metallurgy
Palladium‐catalyzed cross‐coupling reactions of 2‐bromocyclohex‐1‐enyl triflates 7 and 11 with a variety of alkenylstannanes occurred chemoselectively at the site of the triflate leaving group to give bromobutadienes which readily underwent Heck reactions with acrylates and styrene. Both steps could be performed in the same flask to give differentially functionalized hexatrienes in up to 88 % overall yield. With simple stannanes, the same catalyst precursor could be used for both coupling steps making it possible to perform the whole sequence with only one portion of catalyst. For some of the functionally substituted stannanes, specifically adjusted catalyst systems had to be used. The 1,3,5‐hexatrienes obtained were further transformed, in particular the methoxy‐substituted compounds 14 a – c were converted to bicyclo[4.4.0]decenones 30 (71–97 %), bicyclo[4.3.0]nonenones 35 (74–93 %), cyclodecynone 37 a (47 %), and cyclononynone 39 a (15 %). Thermal electrocyclizations of the other hexatrienes gave tetrahydronaphthalines 31 (60–61 %), the tricyclic lactone 32 (72–75 %) and decahydrophenanthrene 33 (75 %) in good yields.