16198-39-3Relevant academic research and scientific papers
Intramolecular reactivity of functionalized arylcarbenes: 2-Allyloxyphenylcarbenes
Gotzhein, Frank,Kirmse, Wolfgang
, p. 1373 - 1376 (2007/10/03)
2-Allyloxyphenylcarbenes (8) undergo intramolecular addition (→ 9) and (formal) C-H insertion (→ 11) competitively. Stereochemical labels indicate that 11 and major amounts of 9 arise from triplet 8. The intermolecular O-H insertion of singlet 8 with meth
cis-Oxypalladation Complexes Derived from (1R,5R)-2(10),3-Pinadiene and Their Utilization in Pd(II)-catalyzed Enantioselective Cyclization of 2-(trans-2-Butenyl)phenols
Hosokawa, Takahiro,Imada, Yasushi,Murahashi, Shun-Ichi
, p. 3282 - 3290 (2007/10/02)
(1R,5R)-2(10),3-Pinadiene, when treated with either Na2PdCl4 in MeOH or Pd(OAc)2 in AcOH and NaCl, gives di-μ-chloro-bis (4a) or (4b), respectively.These complexes represent the firstly isolated cis-oxypalladation adduct.The ligand exchange of 4b with AgOAc affords di-μ-acetato-bis (5b) which serves as the catalyst for the asymmetric cyclization of 2-(trans-2-butenyl)phenols leading to 2-vinyl-2,3-dihydrobenzofurans (13).Although the enantioselectivities induced in this asymmetric cyclization are not high (1-29percent ee), noteworthy is that the cis-complex 5b affords (R)-(-)-enantiomer of 13 while the parent di-μ-acetato-bis give the (S)-isomer.As an application of the present asymmetric cyclization, attempts to synthesize (S)-(+)-tremetone have been made.
MODIFICATION OF THE NICKL REACTION. A GENERAL SYNTHETIC APPROACH TO 2-VINYL-2,3-DIHYDROBENZOFURANS
Bigi, Franca,Casiraghi, Giovanni,Casnati, Giuseppe,Sartori, Giovanni
, p. 169 - 174 (2007/10/02)
The annelation reaction of metal phenolates 1 with 1,4-dibromo-2-butenes 2 to give 2-vinyl-2,3-dihydrobenzofuran derivatives 3 (Nickl reaction) was critically examined and markedly improved.Use of lithium phenolates, instead of sodium phenolates, as substrates and toluene, instead of methanol, as reaction medium, caused the yield of annelated compounds to rise dramatically.The relevance of this modified route to the synthesis of Euparinoid 2,3-dihydrobenzofurans and their synthetic analogues was emphasized.
Palladium(II)-catalyzed asymmetric oxidative cyclization of 2-allylphenols in the presence of copper(II) acetate and molecular oxygen. Study of the catalysis of the Wacker-type oxidation
Hosokawa, Takahiro,Uno, Tetsuyuki,Inui, Shiro,Murahashi, Shun-Ichi
, p. 2318 - 2323 (2007/10/02)
The intramolecular oxidative cyclization of trans-2-(2-butenyl)phenol (2) using (+)-(3,2,10-η-pinene)palladium(II) acetate (1) in the pressure of Cu(OAc)2 and O2 has been studied in order to gain insight into the catalysis of the Wacker-type oxidation. The main results obtained are as follows: (1) the catalytically active Pd(II) species which is different from complex 1 is formed during the reaction, (2) the chiral pinanyl ligand is retained by the catalyst throughout the reaction, and (3) the catalyst consists of copper and palladium linked with an acetate bridge. These results cannot be accounted for by the conventional Wacker-type catalysis involving the reoxidation of palladium(0). A hydroperoxopalladium(II) species coupled with copper(II) acetate is most likely the active catalyst in the present reaction. A mechanism for the enantioselection is also described in comparison with the results obtained by the oxidative cyclization of cis-2-(2-butenyl)phenol.
