α-Lithioenamines by chlorine-lithium exchange: versatile acyl anion equivalents

Abstract

The reaction of α-chloroenamines 1 with an excess of lithium and a catalytic amount of 4,4'-ditert-butylbiphenyl (DTBB) in THF at -90 ºC followed by reaction with an electrophile (D 2 O, Me 3 SiCl, PhCOCH=CHPh/BF 3 , CO 2 , CyNCO) and final hydrolysis gave the expected functionalized enamines 2. In the case of aldehydes (t-BuCHO, n-C 5 H 11 CHO, PhCHO) it was necessary to perform the lithiation in the presence of the electrophile (Barbier conditions) at -40 ºC. Hydrolysis of the obtained enamines either with silica gel or with hydrochloric acid yielded the expected functionalized ketones 3.

Thiazolium‐Catalyzed Additions of Acylsilanes: A General Strategy for Acyl Anion Addition Reactions.

“…Purified with 10% ether/hexanes yielding 40 mg (63 %) of 18 as a clear oil. R f = 0.48 (40/60 ether/hexanes); IR (film): 3059, 2929, 1721, 1664, 1605, 1576 cm -1 ; 1 H NMR (500 MHz, CDCl 3 ) δ 8.06-7.97 (m, 4H), 7.68-7.29 (m, 6H), 4.60 (dd, J = 10.1, 2.9 Hz, 1H), 4.01 (dd, J = 19.8, 10.4 Hz, 1H), 3.09 (dd, J = 17.9, 3.11 Hz, 1H), 2.53 (m, 1H), 2.15 (m, 1H), 1.81 -1.09 (m, 9H); 13 C NMR (125 MHz, CDCl 3 ) δ 212.5, 198.5, 138.5, 133.4, 130.8, 129.3, 129.2, 128.9, 128.4, 127.6, 52.0, 50.8, 43.0, 29.7, 28.6, 26.2, 26.1; All spectral data match those reported by Yus and coworkers 12. …”

“…9. 1 H and 13 C Spectra S20-S90 1,2,4-Triphenylbutane-1,4-dione (4) S20-S21 4-(4-chlorophenyl)-1-2-diphenylbutane-1-4-dione (5) S22-S23 4-(4-methoxyphenyl)-1,2-diphenylbutane-1-4-dione (6) S24-S25 2-(Naphthalene-4-yl)-1,4-diphenylbutane-1,4-dione (7) S26-S27 2-(4-Bromophenyl)-1,4-diphenylbutane-1,4-dione (8) S28-S29 2-(4-Chlorophenyl)-1,4-diphenylbutane-1,4-dione (9) S30-S31 2-(2-Chlorophenyl)-1,4-diphenylbutane-1,4-dione (10) S32-S33 (2-(4-Methylphenyl)-1,4-diphenylbutane-1-4-dione (11) S34-S35 2-(3-Methoxyphenyl)-1,4-diphenylbutane-1,4-dione (12) S36-S37 2-(4-Methoxyphenyl)-1,4-diphenylbutane-1,4-dione (13) S38-S39 1-(4-chlorophenyl)-2-4-diphenylbutane-1,4-dione (15) S40-S41 2,4-diphenyl-1-p-tolylbutane-1,4-dione (16) S42-S43 1,3-Diphenylpentane-1,4-dione (17) S44-S45 1-Cyclohexyl-2-4-diphenyl-1-4-dione (18) S46 Diethyl 2-benzoylsuccinate (19) S47-S48 S2 Dimethyl 2-benzoylsuccinate (20) S49-S50 1-Phenylpentane-1,4-dione (22) S51-S52 1-(4-chlorophenyl)-2-phenylpentane-1,4-dione (23) S53-S54 2, 3, 5 triphenylfuran ( 25 General Methods: Tetrahydrofuran (THF), dicholormethane (DCM) and chloroform were purified by passage through a bed of activated alumina. 1 Purification of reaction products was carried out by flash chromatography using silica gel 60 (230-400 mesh).…”