ChemInform Abstract: Diastereoselective Synthesis of Highly Substituted Five-Membered-Ring Oxygen Heterocycles by Zirconocene-Mediated C-C Coupling Reactions.

ChemInform ◽  
2010 ◽  
Vol 29 (45) ◽  
pp. no-no
Author(s):  
D. ENDERS ◽  
M. KROLL ◽  
G. RAABE ◽  
J. RUNSINK
Keyword(s):  
Membered Ring ◽  
Coupling Reactions ◽  
Diastereoselective Synthesis ◽  
Oxygen Heterocycles

scholarly journals Studies on the transannular Diels–Alder reaction of 15-membered macrocyclic trienes containing a trans-trans diene. Part I: Synthesis and isomerization of various model cyclopentadecatrienes

1995 ◽  
Vol 73 (10) ◽  
pp. 1675-1694 ◽  
Author(s):  
Dennis G. Hall ◽  
Renate Müller ◽  
Pierre Deslongchamps
Keyword(s):  
Aqueous Media ◽  
Alder Reaction ◽  
Membered Ring ◽  
Diels Alder ◽  
Coupling Reactions ◽  
Diels Alder Reaction ◽  
Trans Diene

The transannular Diels–Alder reaction of 15-membered macrocyclic trienes with a trans-trans-cis (TTC) olefin geometry can lead to A.B.C.[6.6.7] tricyclic products of trans-syn-trans (TST) and cis-syn-cis (CSC) stereochemistry whereas the TTT isomers can produce the trans-anti-cis (TAC) and cis-anti-trans (CAT) tricycles. In order to study the influence of the position (pro-6.6 or pro-6.7) and the nature (alkyl, alkoxymethyl, or formyl) of the dienophile substituent, a set of 10 model cyclopentadecatrienes was prepared. The synthesis of appropriately functionalized trisubstituted dienophile and diene synthons, as well as their coupling reactions affording acyclic precursors, is described in this paper (first in a series of two). A mild and efficient macrocyclization protocol yielded the required methyl- or alkoxymethyl-substituted cyclic substrates. Further transformations led to the formyl-substituted ones. In particular, the TTT macrocycles containing an enal as a dienophile could be completely isomerized to the corresponding TTC thermodynamic isomers in acidic aqueous media. Keywords: transannular, Diels–Alder, 15-membered ring, A.B.C.[6.6.7] tricycles, diterpene.

scholarly journals Palladium-Catalysed Coupling Reactions En Route to Molecular Machines: Sterically Hindered Indenyl and Ferrocenyl Anthracenes and Triptycenes, and Biindenyls

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1950 ◽  
Author(s):  
Michael J. McGlinchey ◽  
Kirill Nikitin
Keyword(s):  
Time Scale ◽  
Molecular Machines ◽  
Suzuki Coupling ◽  
Membered Ring ◽  
Coupling Reactions ◽  
Rotation Barrier ◽  
Sterically Hindered ◽  
Molecular Brake

Pd-catalysed Stille and Suzuki cross-couplings were used to prepare 9-(3-indenyl)-, 6, and 9-(2-indenyl)-anthracene, 7; addition of benzyne led to the 9-Indenyl-triptycenes, 8 and 9. In 6, [4 + 2] addition also occurred to the indenyl substituent. Reaction of 6 through 9 with Cr(CO)6 or Re2(CO)10 gave their M(CO)3 derivatives, where the Cr or Re was complexed to a six- or five-membered ring, respectively. In the 9-(2-indenyl)triptycene complexes, slowed rotation of the paddlewheel on the NMR time-scale was apparent in the η5-Re(CO)3 case and, when the η6-Cr(CO)3 was deprotonated, the resulting haptotropic shift of the metal tripod onto the five-membered ring also blocked paddlewheel rotation, thus functioning as an organometallic molecular brake. Suzuki coupling of ferrocenylboronic acid to mono- or dibromoanthracene yielded the ferrocenyl anthracenes en route to the corresponding triptycenes in which stepwise hindered rotations of the ferrocenyl groups behaved like molecular dials. CuCl2-mediated coupling of methyl- and phenyl-indenes yielded their rac and meso 2,2′-biindenyls; surprisingly, however, the apparently sterically crowded rac 2,2′-Bis(9-triptycyl)biindenyl functioned as a freely rotating set of molecular gears. The predicted high rotation barrier in 9-phenylanthracene was experimentally validated via the Pd-catalysed syntheses of di(3-fluorophenyl)anthracene and 9-(1-naphthyl)-10-phenylanthracene.

Enantio- and diastereoselective synthesis of tetrahydrofuro[2,3-b]furan-2(3H)-one derivatives and related oxygen heterocycles via an asymmetric organocatalytic cascade process

2017 ◽  
Vol 4 (12) ◽  
pp. 2358-2363 ◽  
Author(s):  
Wei-Wei Zhao ◽  
Yan-Kai Liu
Keyword(s):  
Cascade Process ◽  
Diastereoselective Synthesis ◽  
Single Operation ◽  
Oxygen Heterocycles

Tetrahydrofuro[2,3-b]furan-2(3H)-one derivatives were formed via a novel asymmetric organocatalytic cascade process with excellent stereoselectivity in one single operation.

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