34455-70-4Relevant academic research and scientific papers
Reductive Cyclization of Ketones Tethered to Activated Olefins Mediated by Magnesium in Methanol
Lee, Ge Hyeong,Choi, Eun Bok,Lee, Eun,Pak, Chwang Siek
, p. 1428 - 1443 (2007/10/02)
The reductive cyclization of various ketones tethered to activated olefins such as α,β-unsaturated esters, nitriles, sulfoxides, and sulfides mediated by magnesium in dry methanol in the presence of mercuric chloride.When traeted with magnesium in dry methanol at -23 deg C all of the ketones except nitrile 9 (42percent) and 5-oxa-8-keto-2-enoate 5 (13percent) gave excellent yields (79-98percent) of mono- and bicyclic alcohol products resulting from carbon-carbon bond formation between the β-carbon of the activated olefin and the carbonyl carbon.The reaction was accelerated by the catalytic amount of mercuric chloride, although the stereoselectivity was not affected by the catalyst.For all the substrates except 8-keto-2-enoate 3 and 5-aza-8-keto-2-enoate 6, the configuration of the major product was trans between the hydroxy and (methoxycarbonyl)methyl groups.The product isomer ratios were independent of the substrate geometry (E or Z).In contrast to the ketones, aldehydes tethered to α,β-unsaturated esters gave products of simple reduction of the double bond and/or saturated alcohols instead of the cyclized products.When the reaction temperature was lowered, the yields of cyclized product were significantly affected by the production of appreciable amounts of saturated product, but the stereoselectivity was not improved.Under the same reaction conditions α,β-unsaturated sulfoxide 16 gave deoxygenated sulfide 18 (85percent) as the major product along with a small amount (9percent) of cyclized product 19t.In contrast, sulfone 17 underwent desulfonylation instead of cyclization to give olefin 20 (54percent).With excess magnesium (15 equiv), however, α,β-unsaturated sulfoxide 16 gave cyclized sulfide 19t (95percent) via deoxygenated sulfide 18.Both 16Z and 16E afforded product 19t as a single isomer.It is suggested that the reductive cyclization of the α,β-unsaturated esters and nitriles proceed by means of nucleophilic attack of a β-carbon radical anion, formed by initial electron transfer from magnesium metal to the activated olefin, on the carbonyl group.The cyclization of the α,β-unsaturated sulfide proceeds by nucleophilic attack of the ketyl on the olefinic double bond.
OZONOLYSIS OF ALKENES AND REACTIONS OF POLYFUNCTIONAL COMPOUNDS. XVIII. INVESTIGATION OF A NEW OZONOLYTIC SYNTHESIS OF CARBOXYLIC ACIDS
Odinokov, V. N.,Botsman, L. P.,Ishmuratov, G. Yu.,Tolstikov, G. A.
, p. 453 - 463 (2007/10/02)
By identification of the 18O isotope label in the oligomeric peroxide obtained by ozonization of a cyclic olefin in the presence of heavy oxygen and also in the product from catalytic isomerization of this peroxide ( the α,ο-dicarboxylic acids or its dimethyl ester ) it was shown that oxygen enters the ozonolysis product when the reaction is carried out in ether solvents.It is suggested that the increased content of active oxygen in the ozonolysis peroxy product is due to oxidation of the ether solvent to form α-hydroperoxide and addition of the latter to the oligomeric zwitterion, solvated by the polar solvents.It was established that the catalytic and thermal isomerization of the oligomeric peroxides and ozonides of cyclic olefins to the α,ο-dicarboxylic acids and ο-formyl carboxylic acids occurs through the oligomeric α-hydroxy peresters and α-hydroxy esters respectively.
