Naphthalene-catalysed lithiation of carbamoyl and thiocarbamoyl chlorides under Barbier-type reaction conditions
作者:Diego J. Ramón、Miguel Yus
DOI:10.1016/0040-4020(96)00827-7
日期:1996.10
The reaction of different carbamoyl or thiocarbamoyl chlorides 1 with carbonyl compounds or imines 2 in the presence of an excess of lithium powder and a catalytic amount of naphthalene (3 mol %) in THF at −78°C leads, after hydrolysis with water, to the expected α-hydroxy or α-amino amides 3, respectively. In the case of allylic or benzylic derivatives 1a,c, when longer reaction times are used, the
Seebach,D. et al., Chemische Berichte, 1976, vol. 109, p. 1309 - 1323
作者:Seebach,D. et al.
DOI:——
日期:——
Carbamoyl and thiocarbamoyl lithium: A new route by naphthalene-catalysed chlorine-lithium exchange
作者:Diego J. Ramón、Miguel Yus
DOI:10.1016/s0040-4039(00)61613-1
日期:1993.10
The reaction of N,N-diisopropylcarbamoyl or N,N-dimethylthiocarbamoyl chloride (1a or 1b) with an excess of lithium powder and a catalytic amount of naphthalene (3 mol %) in the presence of a carbonyl compound 2 at temperatures ranging between -78 and 20-degrees-C, under Barbier-type conditions leads, after hydrolysis with water, to the corresponding alpha-hydroxy amides or thioamides 3, respectively.
Reaction of Benzylic α-Hydroxythioamides with Thionyl Chloride
作者:Xavier Creary、Jennifer Tricker
DOI:10.1021/jo971590v
日期:1998.7.1
9-Hydroxy-9-(N,N-dimethylthiocarbamyl)fluorene,4, reacts very rapidly with 1 equiv of thionyl chloride to give the corresponding alpha-chlorothioamide derivative, 2. However reaction of 4 with 2 equiv of thionyl chloride gives the desulfurized product 9-chloro-9-(N,N-dimethylcarbamyl)fluorene 6. This unusual desulfurization reaction, which is neither completely general nor completely understood at the present time, occurs less readily than initial formation of the alpha-chlorothioamide. The a-chlorothioamide 2 is highly reactive in hydroxylic solvents. The substantially less reactive alpha-chloroamide 6 undergoes reaction in hydroxylic solvents via the intermediacy of the 9-(N,N-dimethylcarbamyl)-9-fluorenyl cation, 15, at rates comparable to those of the or-H analogue, 9-chlorofluorene, 14. Computational studies indicate that the cl-carbonyl cation 15 prefers a conformation in which the carbonyl group is rotated 90 degrees with respect to the fluorenyl system. The relatively rapid rate of solvolysis of 6 is attributed to relief of ground-state strain as the cation 15 forms, as well as delocalization involving the fluorene system. Carbonyl conjugation as a cation-stabilizing feature does not appear to operate in the alpha-carbonyl cation 15.
ABLENAS, F. J.;GEORGE, B. E.;MALEKI, M.;JAIN, R.;HOPKINSON, A. C.;LEE-RUF+, CAN. J. CHEM., 65,(1987) N 8, 1800-1803
作者:ABLENAS, F. J.、GEORGE, B. E.、MALEKI, M.、JAIN, R.、HOPKINSON, A. C.、LEE-RUF+