Luche reduction<\/strong>\u00a0is the selective\u00a0organic reduction\u00a0of\u00a0ketones\u00a0to\u00a0alcohols\u00a0with\u00a0lanthanoid\u00a0chlorides\u00a0such as\u00a0cerium(III chloride\u00a0andsodium borohydride. The Luche reduction can be conducted\u00a0chemoselectively<\/a>\u00a0toward\u00a0ketone\u00a0in the presence of\u00a0aldehyde\u00a0or toward\u00a0\u03b1,\u03b2-unsaturated ketone<\/a>\u00a0in the presence of non-conjugated\u00a0ketone.^{1,2,,3<\/sup><\/p>\n}

An\u00a0enone<\/a>\u00a0forms an\u00a0allyl alcohol\u00a0in a 1,2-addition. Competing conjugate 1,4-addition is suppressed. The solvent is an\u00a0alcohol\u00a0such asmethanol\u00a0or\u00a0ethanol.<\/p>\n

\n

<\/a><\/dd>\n<\/dl>\n

The selectivity can be explained in terms of\u00a0HSAB theory<\/a>: carbonyl groups require hard nucleophiles for 1,2-addition. The hardness of the borohydride is increased by replacing hydride groups with alkoxide groups, a reaction catalyzed by the cerium salt by increasing the\u00a0electrophilicity\u00a0of the carbonyl group. This is selective for ketones because it is more Lewis basic.<\/p>\n

In one application a ketone is selectively reduced in presence of an\u00a0aldehyde. Actually in presence of methanol as solvent, the aldehyde forms methoxy acetal which is inactive in the reducing conditions.<\/p>\n

\n

<\/a><\/dd>\n

References<\/strong><\/em><\/dd>\n<\/dl>\n

\n

\n
1. Strategic Applications of Named Reactions in Organic Synthesis (Paperback) by Laszlo Kurti, Barbara Czako\u00a0ISBN 0-12-429785-4<\/a><\/li>\n
2. Lanthanides in organic chemistry. 1. Selective 1,2 reductions of conjugated ketones<\/em>\u00a0Jean Louis Luche\u00a0J. Am. Chem. Soc.<\/a>;\u00a01978<\/strong>; 100(7); 2226-2227.\u00a0doi<\/a>:10.1021\/ja00475a040<\/a><\/li>\n
3. Lanthanoids in organic synthesis. 6. Reduction of .alpha.-enones by sodium borohydride in the presence of lanthanoid chlorides: synthetic and mechanistic aspects<\/em>\u00a0Andre L. Gemal, Jean Louis Luche\u00a0J. Am. Chem. Soc.<\/a>;\u00a01981<\/strong>; 103(18); 5454-5459doi<\/a>:10.1021\/ja00408a029<\/a><\/li>\n<\/ol>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

   Luche reduction\u00a0is the selective\u00a0organic reduction\u00a0of\u00a0ketones\u00a0to\u00a0alcohols\u00a0with\u00a0lanthanoid\u00a0chlorides\u00a0such as\u00a0cerium(III chloride\u00a0andsodium borohydride. The Luche reduction can be conducted\u00a0chemoselectively\u00a0toward\u00a0ketone\u00a0in the presence of\u00a0aldehyde\u00a0or toward\u00a0\u03b1,\u03b2-unsaturated ketone\u00a0in the presence of non-conjugated\u00a0ketone.1,2,,3 An\u00a0enone\u00a0forms an\u00a0allyl alcohol\u00a0in a 1,2-addition. Competing conjugate 1,4-addition is suppressed. The solvent is an\u00a0alcohol\u00a0such asmethanol\u00a0or\u00a0ethanol. The selectivity can be explained in terms of\u00a0HSAB theory: carbonyl groups require hard nucleophiles for 1,2-addition. The… Continue reading Luche reduction<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,4],"tags":[143,9],"_links":{"self":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts\/223"}],"collection":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/comments?post=223"}],"version-history":[{"count":2,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts\/223\/revisions"}],"predecessor-version":[{"id":225,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/posts\/223\/revisions\/225"}],"wp:attachment":[{"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/media?parent=223"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/categories?post=223"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/amcrasto.theeurekamoments.com\/wp-json\/wp\/v2\/tags?post=223"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}