Arylation of 8-Acetoxyoctalenone in a Nickel-Catalyzed Coupling Reaction with Lithium Arylborates

Abstract

In order to find a suitable organometallic compound and a catalyst for the arylation of 8-acetoxyoctalenone 4 (a stereoisomeric mixture of 4α and 4β), phenylation was first investigated with PhZnX (7: X = Cl; 8: X = Br)/Pd or Ni cat., PhSnBu 3 (9)/Pd cat. and LiCl, and [PhB(Bu)(OCHMeCHMeO)]Li (10a)/Ni cat. Borate 10a provided the desired prod-

Property Tuning in Charge‐Transfer Chromophores by Systematic Modulation of the Spacer between Donor and Acceptor

“…On the way to chromophores 4 a, b with a central hexa‐1,5‐dien‐3‐yne‐1,6‐diyl spacer, the intermediate enynes 10 a, b were prepared from 3‐(trimethylsilyl)propargyl alcohol by PCC oxidation12 and Corey–Fuchs dibromoolefination8c, 13 to give 9 , followed by Suzuki cross‐coupling14 with 4‐(dimethylamino)phenylboronic acid15 or Sonogashira cross‐coupling with 4‐ethynyl‐ N,N ‐dimethylaniline (Scheme ). Removal of the Me 3 Si group in 10 b and direct lithiation was accomplished with MeLi⋅LiBr,16 and reaction with DMF, followed by pouring the mixture into aqueous phosphate buffer,17 surprisingly provided the remarkably stable aldehyde 11 , which was characterized by X‐ray analysis (see http://www.wiley-vch.de/contents/jc_2111/2007/f601735_s.pdf).…”

“…4-(Dimethylamino)phenylboronic acid was synthesized from 4-bromo-N,N-dimethylaniline following literature procedure in 61 % yield. [15] 4-Ethynyl-N,N-dimethylaniline was prepared from 4-iodo-N,N-dimethylaniline and trimethylsilylacetylene by Sonogashira cross-coupling reaction and final Me 3 Si group removal (K 2 CO 3 , MeOH) in 92 % overall yield. Compounds 1 a, [6] 1 b, [4b] 2 a, [7] and 7 [8] were prepared according to literature procedure.…”

New Push‐Pull Chromophores Featuring TCAQ (11,11,12,12‐Tetracyano‐ 9,10‐anthraquinodimethane) and Other Dicyanovinyl Acceptors

“…On the way to 2 ( n = 0, 1), dibromoolefination of commercially available 1,4‐dioxaspiro[4.5]decan‐8‐one furnished 4 (Scheme ) 16. Removal of the acetal protecting group17 and subsequent Sonogashira18 or Suzuki19 cross‐coupling on 5 , using 4‐ethynyl‐ N , N ‐dimethylaniline or [4‐(dimethylamino)phenyl]boronic acid,20 afforded donor‐substituted cyclohexanones 6 and 7 , respectively. Al 2 O 3 ‐catalyzedKnoevenagel condensation21 with malononitrile smoothly provided 8 and 9 in good yields.…”

“…The most important signals are reported in m / z units with M as the molecular ion. [4‐(Dimethylamino)phenyl]boronic acid was synthesized from 4‐bromo‐ N , N ‐dimethylaniline, according to a literature procedure, in 61 % yield 20. 4‐Ethynyl‐ N , N ‐dimethylaniline and 4‐ethynyl‐ N , N ‐dihexylaniline were prepared from 4‐iodo‐ N , N ‐dimethylaniline or 4‐iodo‐ N , N ‐dihexylaniline and trimethylsilylacetylene by Sonogashira cross‐coupling and final Me 3 Si group removal (K 2 CO 3 , MeOH) in 92 % and 78 % overall yields, respectively.…”