- Stereoselective preparation of functionalized acyclic alkenylmagnesium reagents using i-PrMgCl-LiCl
-
(Chemical Equation Presented) Acyclic functionalized alkenyl iodides are converted with high stereoselectivity to the corresponding functionalized alkenylmagnesium derivatives by the reaction with i-PrMgCl-LiCl between -40 and -20°C. Functional groups such as a nitrile, chloride, iodide, and ester are readily tolerated. The conversion of an alkenyl iodide bearing a keto group to the corresponding silylated cyanohydrin allows preparation of the corresponding Grignard reagent affording, after acylation and deprotection, unsaturated 1,4-diketones.
- Ren, Hongjun,Krasovskiy, Arkady,Knochel, Paul
-
p. 4215 - 4217
(2007/10/03)
-
- Stereoselective Conjugate Addition of Halide Anion to Acetylenic Carbonyl Compounds Promoted by Lanthanoid Reagents
-
The conjugate addition of halide anion to acetylenic ketones proceeded by the combined use of cerium salts, halotrimethylsilanes and sodium or tetrabutylammonium salts to afford trans-β-halo enones stereoselectively.On the other hand, N,N-diethyl cis-β-haloacrylamides were synthesized from propiolamide.
- Fujisawa, Tamotsu,Tanaka, Akihito,Ukaji, Yutaka
-
p. 1255 - 1256
(2007/10/02)
-
- β-HALOVINYL KETONES: SYNTHESIS FROM ACETYLENIC KETONES
-
The reaction of terminal acetylenic ketones with NaI or LiBr gave almost exclusively E-β-iodo-or E-β-bromovinyl ketones in trifluoracetic acid, while Z-β-iodo or Z-β-bromovinyl ketones were the major products in acetic acid.Trimethylsilyl iodide and bromide reacted smoothly with acetylenic ketones at -78 deg C to give TMS-allenolates which were readily converted to β-iodo and β-bromovinyl ketones, respectively.
- Taniguchi, Mikio,Kobayashi, Shozo,Nakagawa, Masako,Hino, Tohru,Kishi, Yoshito
-
p. 4763 - 4766
(2007/10/02)
-
- ALDOL REACTION OF ALLENOLATES GENERATED VIA 1,4-ADDITION OF IODIDE ANION OR ITS EQUIVALENT TO α,β-ACETYLENIC KETONES
-
TMSI, Et2AlI, and (n-Bu)4NI/TiCl4 smoothly added to α,β-acetylenic ketones in a 1,4-fashion to yield allenolates 2, which reacted with aldehydes providing aldol adducts in good overall yield.A high Z-stereoselectivity was achieved by use of (n-Bu)4NI/TiCl4 at -78 deg C, while a high E-stereoselectivity occured at 0 deg C.
- Taniguchi, Mikio,Hino, Tohru,Kishi, Yoshito
-
p. 4767 - 4770
(2007/10/02)
-