Alkenones, addition reactions

The catalyst derived from chlorine displacement was effective in the base catalysed ring-opening of epoxides to form monoglycerides.[16] The other TBD-derived catalyst (from epoxide ring-opening) was also found to be active in the Knoevenagel reaction, the Michael addition and the base catalysed epoxidation of alkenones.[15] Results in the epoxidation reaction were of particular interest, as this leads to highly labile and... 

Dieb-AUer catalyst. Aluminum chloride catalyzes the reaction of 2-cyclo-alkenones (1) with 1,3-butadiene to give bicyclic ketones in satisfactory yields. The rate of the addition and the yields are strongly dependent on the quantity of catalyst. When less than 0.3 equiv. of AICI3 is used, the rate and yield are low when more than 1 equiv. is used, the desired reaction fails. When R = H, the initial cis-adducts isomerize to the frans-isomers. ... 

Conjugate addition of methyllithium with cyclic alkenone was mediated by aminoalcohol 10 having a bomane skeleton, and afforded the corresponding methyl adduct in excellently high ee (Eq. (12.15)) [39]. Although the reaction needs a stoichiometric amount of chiral alcohol, a batch process was applicable to mimic the catalytic process. 

By use of an amino alcohol having a bornane skeleton (7) the conjugate addition of methyllithium to cyclic alkenones to afford the corresponding methyl adduct in excellently high ee was realized (Scheme 7). Although these reactions need a stoichiometric amount of the chiral alcohol, batch process techniques are applicable in the reaction [31,32]. 

NaB(OMe)4, easily prepared fromNaBH4 and methanol, was found to be a mild catalyst for various Michael additions at room temperature. The reaction was applicable to a wide variety of nucleophiles and Michael acceptors, providing products in good to excellent yields (69-100%). Baylis-Hillman adducts could be reduced by NaBH4 with a catalytic amount of InCls (13 mol%) to give the corresponding trisubstituted (E)-alkenones chemo-... 

In Scheme 1.2, all of the types of carbonylations that are discussed in the book are depicted. Alcohols, amines, ethers, carboxylic acids and halides can be converted to acids, amides, esters, ketones, alkynones, alkenones, anhydrides and acid halides with the assistance of transition metal catalysts in the presence of a CO source. The CO sources used can be carbon monoxide gas, Mo(CO)6, Co(CO>6, formic acid, aldehyde, etc. If the starting material is alcohols or amines, some additives for activation are needed, such as BuONO, TsCl, AcCl. If the substrate is (Hetero)ArH, additional oxidants will be necessary this is a so-caUed oxidative carbonylation. If an unsaturated compound is to be carbonylated, a nucleophile NuH that carries an acidic hydrogen has to be present. In the case of insertion reactions, this is not necessary. 

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