Journal of Organic Chemistry p. 1428 - 1443 (1994)
Update date:2022-09-26
Topics:
Lee, Ge Hyeong
Choi, Eun Bok
Lee, Eun
Pak, Chwang Siek
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.
View MoreWeifang Arylchem Chemical Co., LTD
Contact:86-536-5217866
Address:Development Zone, Shouguang, Shandong Province
Contact:86 513 85512619
Address:Rm.1306, Building A, Wenfeng Mansion,168 Gongnong Road, Nantong Jiangsu China
ShanDong XinDa Chemical CO.,LTD(expird)
Contact:086-0311-87580543
Address:No.168, High Technology Development Zone Jinan Shandong China
SHOUGUANG BOYU CHEMICAL CO.,LTD
Contact:+86-536-8256719
Address:ROOM 1101&1103,BUILDING D,ZHONGTU MANSION,NO.6565 EAST FUSHOU STREET,WEIFANG CITY,SHANDONG,CHINA.
SHIJIAZHUANG HENRYTE CHEMICALS CO,.LTD(expird)
Contact:+86-311-85208698 311-80837698
Address:NO.166, yuhua west road, SHIJIAZHUANG, China
Doi:10.1055/s-1980-29189
(1980)Doi:10.1016/S0040-4039(00)92800-4
(1980)Doi:10.1246/cl.1982.741
(1982)Doi:10.1016/0009-2614(82)83343-5
(1982)Doi:10.1021/jm00188a003
(1979)Doi:10.1021/jm00136a012
(1981)