Carbonyls conjugate additions, acetylene

Addition of NaX or BuJNX to l-alkyn-3-ones.1 In the presence of these two reagents, sodium or ammonium salts undergo conjugate addition to acetylenic carbonyl compounds. This reaction provides mm-P-halovinyl ketones or N,N-diethyl m-P-haloacrylamides. 

Heasley VL, Buczala DM, Chappell AE, Hill DJ, Whisenand JM, Shellhamer DF (2002) Addition of bromine chloride and iodine monochloride to carbonyl-conjugated, acetylenic ketones synthesis and mechanisms. J Org Chem 67 2183-2187... 

Conjugate addition is also a feature of the reaction of organocuprates with a,p-acetylenic carbonyl compounds. By conducting the reaction at —78 °C, high yields of cis addition compounds can be obtained (1.163). This allows the stereocontrolled... 

Several syntheses of aldehydes and ketones based on the insertion of carbon monoxide have been reported. Reaction of norbornadiene with monosubstituted acetylenes in the presence of octacarbonyldicobalt gives the fused cyclopen-tenone (35) in high yield conjugate addition of a cuprate and vacuum pyrolysis completes a simple synthesis of 2,3-disubstituted cyclopent-4-enones (36) (Scheme 30)." Conjugated dienes with methyl iodide in the presence of the same cobalt reagent yield conjugated dienones (37) [equation (8)]." In a review of carbonyl insertion reactions, the same reagent is reported to catalyse the reaction... 

Conjugate Addition. Catalytic asymmetric conjugate addition of acetylenes to a. -unsaturated carbonyl confounds is one of the most challenging tasks in organic chemistry and TIPS-acetylene has been used as a useful tool reagent to confirm the viability of the developed protocols. Rh(I)-catalyzed conjugate alkynylation has been extensively developed by Hayashi and coworkers. Asymmetric conjugate addition of TIPS-acetylene was accomplished via a Rh(T) catalysis (eq 28) and the effects of the alkyl substituents on the sUylacetylenes were examined for their... 

A variety of routes have been employed to produce several different six-membered cyclic imino-oxysulphuranes. The sulphoximine (145) was obtained by conjugate addition of a sulphoximine to phenylbenzoyl-acetylene. A 3-carbonyl derivative (14Q was obtained by employing the... 

Compounds containing a double or triple bond, usually activated by additional unsaturation (carbonyl, cyano, nitro, phenyl, etc.) In the ap position, add to the I 4-positions of a conjugated (buta-1 3-diene) system with the formation of a ax-membered ring. The ethylenic or acetylenic compound is known as the dieTwphile and the second reactant as the diene the product is the adduct. The addition is generally termed the Diels-Alder reaction or the diene synthesis. The product in the case of an ethylenic dienophile is a cyctohexene and in that of an acetylenic dienophile is a cyctohexa-1 4-diene. The active unsaturated portion of the dienophile, or that of the diene, or those in both, may be involved in rings the adduct is then polycyclic. 

In certain cases, Michael reactions can take place under acidic conditions. Michael-type addition of radicals to conjugated carbonyl compounds is also known.Radical addition can be catalyzed by Yb(OTf)3, but radicals add under standard conditions as well, even intramolecularly. Electrochemical-initiated Michael additions are known, and aryl halides add in the presence of NiBr2. Michael reactions are sometimes applied to substrates of the type C=C—Z, where the co-products are conjugated systems of the type C=C—Indeed, because of the greater susceptibility of triple bonds to nucleophilic attack, it is even possible for nonactivated alkynes (e.g., acetylene), to be substrates in this... 

Substituted cyclopropyl rings conjugated with a triple bond system have recently received attention as C5 building blocks. The procedure described here is a modification of the decarboxylation-elimination reaction for the preparation of a.3 acetylenic acids from enol sulfonates of acyl malonates. Addition of aqueous alkali to the enol sulfonate of diethyl cyclopropyl carbonyl malonate gives cycl opropyl propiol ic acid, but the yield is 1 ow. 

Recently, the transition-metal-catalyzed addition of active methylene C-H bonds to electron-deficient olefins having a carbonyl, a nitrile, or a sulfonyl group has been extensively studied by several research groups. In particular, the asymmetric version of this type of catalytic reaction provides a new route to the enantioselective construction of quaternary carbon centers [88]. Another topic of recent interest is the catalytic addition of active methylene C-H bonds to acetylenes, allenes, conjugate ene-ynes, and nitrile C-N triple bonds. In this section, the ruthenium-catalyzed addition of C-H bonds in active methylene compounds to carbonyl groups and C-C multiple bonds is described. 

Addition to ot, -acetylenic esters and ketones (3, 108 6, 163-164). The addition of organocopper reagents to conjugated acetylenic carbonyl compounds is usually not stereospeciflc, although cis-addition predominates. Japanese chemists have found that the stereoselectivity in the reaction with alkylcopper reagents is markedly enhanced by use of the complex RCu BRj. Thus the reaction of dimethyl acetylenedicarboxylate with n-butylcopper complexed with tri-n-butylboron (or triethylboron) results in exclusive formation of the cis-adduct. In the absence of a trialkylborane the cis- and adducts are formed in the-ratio 85 15. 

Sodium acetylide adds to the carbonyl group of conjugated olefinic aldehydes to give olefinic acetylenic alcohols. Direct addition of acetylene to aldehydes and ketones is catalyzed by copper acetylide (ethynylation ). ... 

The addition of C-H bonds in terminal acetylenes to C-C double bonds in conjugate dienes and a,/3-unsaturated carbonyl compounds can take place with the aid of a... 

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