Carbon-Carbon Bond Formation by the Use of Chloroiodomethane as a C<sub>1</sub>Unit. III. A Convenient Synthesis of the Mannich Base from Enol Silyl Ether by a Combination of Chloroiodomethane and<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-Tetramethylmethanediamine
a combination of chloroiodomethane (CH2ClI) and N,N,N′,N′-tetramethylmethanediamine (TMMD) in DMSO as the solvent at ambient temperature. The mechanism of the transformation is discussed on the basis of product analysis and 1H NMR spectral studies. The reagent system CH2ClI/TMMD also provides a convenient route to the Eschenmoser’s salt (Me2\overset+N=CH2,\overset−I).
The Michael Reaction of Silyl Enol Ethers with α,β-Unsaturated Eetones and Acetals in the Presence of Titanium Tetraalkoxide and Titanium Tetrachloride
Silyl enol ethers react with α,β-unsaturated ketones and esters in the presence of TiCl4 or in the coexistence of TiCl4 and Ti(Oi-Pr)4 to give 1,5-dicarbonyl compounds in good yields. The reactions of acetals derived from α,β-unsaturated ketones with silyl enol ethers in the coexistence of TiCl4 and Ti(Oi-Pr)4, followed by successive addition of 1,2-ethanedithiol, give the Michael products, δ-keto
Regioselective Synthesis of Substituted (3E)-1,3-Dienes from Chelated Allyl-Ironcarbene Complexes and Potassium Enoxyborates
作者:Jutta Böhmer、Frank Hampel、Rainer Schobert
DOI:10.1055/s-1997-1394
日期:1997.6
The addition of potassium enoxyborates to the chelated allyl-iron-carbene complex 1 leads to the corresponding η 4-(3E)-1,3-diene complexes 2 in fair yields. Complexes 2 can be demetalated with ceric ammonium nitrate (CAN) to give unrearranged (3E)-t-oxo-1,3-dienes 3. Prior to decomplexation, the carbonyl group can be further modified. This is demonstrated by the syntheses of the natural terpene alcohol hotrienol and of a complexed methylene-separated dienyne. Potassium enoxyborates are superior to lithium enolates as they are readily prepared in situ from a variety of aldehydes and ketones which do not form sufficiently stable lithium derivatives. In contrast to lithium enolates, only C-C coupling products derived from the "kinetic" regioisomers are formed from unsymmetrical aliphatic ketones.
New Method for the Synthesis of 2‐Aza‐1,3‐Butadienes
作者:Attila Sisak
DOI:10.1080/00397910600946033
日期:2006.12
Abstract 2‐Aza‐1,3‐butadienes have been synthesized from carbonyl compounds and 1,1,1,3,3,3‐hexamethyl‐disilazane in the presence of cobalt‐containing catalysts. The best yields (up to 95%) were achieved in the case of aldehydes branched in the α-position and 2-methylcyclohexanone. In the case of two α,β‐unsaturated ketones, pyridine derivatives were found as the main products.
New Cross Aldol Reactions. Titanium Tetrachloride-promoted Reactions of Silyl Enol Ethers with Carbonyl Compounds Containing A Functional Group
作者:Kazuo Banno
DOI:10.1246/bcsj.49.2284
日期:1976.8
It was found that, in the presence of titanium tetrachloride, silylenolethersselectively react with aldehyde or ketone function of various carbonyl compounds containing another functional group giving the corresponding cross aldols in good yields. The present cross aldol reaction was successfully applied to the synthesis of arturmerone, one of the volatile principles of turmeric oil.