Lithiated ambident anions derivedfrom (1-alkyl-2-propenyl)- or (1-phenyl-2-propenyl)-pentamethyl phosphoric triamides undergo regioselectively γ-reaction with various alkylating reagents and isobutyraldehyde. Further hydrolysis of adducts releases the ketone under acid conditions. Number of synthetic applications clearly show the ketone homoenolate behaviour of these new carbanions.
Cycloaromatization of α-oxoketene dithioacetals and β-oxodithioacetals with benzyl-,1-(naphthylmethyl) and 2-(naphthylmethyl)magnesium halides: Synthesis of condensed polynuclear aromatic hydrocarbons
作者:Ch.Srinivasa Rao、Maliakel P Balu、Hiriyakkanavar Ila、Hiriyakkanavar Junjappa
DOI:10.1016/s0040-4020(01)86411-5
日期:1991.1
An efficient route for the synthesis of substituted naphthalenes, phenanthrenes and other polynuclear aromatic hydrocarbons has been developed. The methodology involves 1,2- (or sequential 1,4- and 1,2-) addition of either benzyl, 1-(naphthylmethyl) or 2-(naphthylmethyl) magnesium halides to α-oxoketenedithioacetals or β-oxodithioacetals followed by borontrifluoride etherate catalyzed cycloaromatization
Regioselective synthesis of substituted 1-methyl- and 2-methylnaphthalenes
作者:K Mallik Yadav、Pramod K Mohanta、Hiriyakkanavar Ila、Hiriyakkanavar Junjappa
DOI:10.1016/0040-4020(96)80832-5
日期:1996.10
Regiospecificallysubstituted 1-methyl- and 2-methylnaphthalenes, 5-methyl- and 6-methyl-1,2,3,4-tetrahydroanthracenes have been synthesized in good yields through 1,2- addition of the corresponding α-lithio-o-or m-xylenes onto α-oxoketenedithioacetals or their dihydro derivatives followed by cyclodehydration of the resulting carbinols in the presence of borontrifluoride etherate.
Theα-oxoketene dithioacetals are shown to undergo conjugate 1,4-reduction in highly regio- and chemoselective manner with sodium borohydride in acetic acid to afford the corresponding β-oxodithioacetals in good yields. These results have been rationalized according to HSAB principle in terms of 'hard soft affinity inversion' concept. The reduction of with sodium cyanoborohydride also proceeds in 1