The complex formed by reaction of Ni(aca& and DiBAH (1:l) catalyzes conjugate addition of dialkylaluminum acetylides to a,@ enones; on hydrolysis, 3-alkynyl ketones are produced in high yield. Through this procedure conjugate addition of alkynyl groups to either S-cis or S-trans enones can be effected. This procedure is the first one which permits conjugate addition of terminal alkynyl units to ordinary S-trans enones. In cases where more than one stereochemical outcome is possible, conjugate addition of alkynyl units gives only one of these. Only 1,4-addition is observed and this only of the alkynyl unit. Complications arising from oxygen substitution in the alkynyl side chain are described.

A study of the mechanism of the ozonation of ethers has been carried out utilizing isotope effect rate studies, competitive relative rate studies on various classes of ethers, and product analysis of ozonations using ozone-oxygen and ozone-nitrogen streams. Results are discussed in terms of both the mode of initial attack of ozone on the system and the varieties of decomposition available to the hydrotrioxide intermediate I. The over-all mechanism is a complicated one involving free radical autoxidation when oxygen is present.

Nickel-Catalyzed Conjugate Addition of Organoaluminum Acetylides to @EnonesSir:Conjugate addition of organometallic compounds to a,@unsaturated ketones is a widely employed reaction in organic synthesis. Organocuprates are commonly employed for 1,4 addition of alkyl and alkenyl groups to a,@-unsaturated ketones;' however, cuprates cannot be used in alkynylation reactions owing presumedly to the strength of the alkynylcopper( I) ligand bond.2 Several sequences have been reported, however, which do achieve conjugate addition of alkynyl units, but each suffers severe limitations. Both acetylenic alanes3 and boranes4 conjugately add to a,@-enones but only to those capable of achieving an s-cis conformation. Of the methods reported which can be applied to fixed S-trans enones (such as 2-cyclohexenone), requires a convenient hydroxyl functional group for direction of intramolecular attack by an alane; the other5 is indirect and involves addition of di(tri-n-butylstanny1)ethylene by cuprate addition and subsequent oxidative elimination of a stannyl group to give, overall, conjugate addition of acetylide to the enone. Extension to alkyl acetylides by this latter method has not been reported. We recently noted6 that a catalyst prepared from Ni(acac)2 and diisobutylaluminum hydride (1 :1) would catalyze the conjugate addition of (a1kenyl)zirconium complexes to a,@-enones. We wish to report herein that this catalyst will, as well, catalyze conjugate addition of terminal alkynyl units to a,@-unsaturated ketones. This procedure is the first one, to the best of our knowledge, which enables this addition to ordinary S-trans enones.A typical procedure for effecting conjugate addition by this route is illustrated as follows.To Ni(acac)2 in ether at 0 O C is added Dibah in toluene solution. The reaction mixture rapidly turns dark red-brown. To this red-brown solution is then added a dialkylaluminum acetylide (prepared in the usual manner from the lithium acetylide and dialkylaluminum chloride)' as a solution in ether. The reaction mixture is cooled to -5 "C and the unsaturated ketone in ethereal solution is added dropwise over a period of 15 min. The reaction mixture is allowed to stir at -5 OC for several hours. Hydrolysis at 0 OC with saturated KH2P04 (aqueous) solution is then followed by addition of just enough of 10% H2S04 (aqueous) to dissolve aluminum salts. The organic layer is washed with saturated N a H C 0 3 and NaCl solutions and is then dried. Removal of solvent and separation of products on silica gel gives the conjugate adduct.

Die aus terminalen Acetylenen mit zunächst Butyl‐Li und nachfolgend Dimethyl‐ AlCl dargestellten Al‐acetylide (I) reagieren in Gegenwart von reduziertem Ni‐acetylacetonat mit ungesättigten Ketonen unter Bildung der Addukte (III).

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