n-allenylation of pyrroles using 1,2,3-trichloropropane

N-ALLENYLATION OF PYRROLES USING 1,2,3-TRICHLOROPROPANE O. A. Tarasova, T. L. Markova, and B. A. Trofimov UDC 542.91:547.748:547.412.614 We have found that 1,2,3-trichloropropane is an efficient allenylating agent for pyrroles in the KOH/DMSO superbase system. Thus, l-propadienyl-2-phenylpyrrole (I) was ob- tained in 62% yield directly from 2-phenylpyrrole. The double dehydrochlorination, nucleo- philic substitution of the chlorine atom by the pyrrolate anion, and prototropic isomeriza- tion of intermediate l-(2-propynyl)-2-phenylpyrrole to an allene were carried out in a sin- gle preparative step with almost 100% selectivity. II,~ H 4 \ / CICH,CHClCtt~Cl /\ / ~- /\ ,'\ Ph N KOll/ DMS0 Ph N H-' H t U IIAC=C=CtI 2 (I) A sample of 5.53 g 1,2,3-trichloropropane was added over i0 min to a mixture of 3.56 g 2-phenylpyrrole, 11.2 g KOH (subjected to prior roasting at 500~ for 4 h), and 50 ml dry DMSO (containing 0.2% H20). Heat was evolved and the temperature rose to 40~ The mixture was then heated for an additional 20 min at 40~ and I00 ml water was added. The reaction mixture was extracted with ether. The ethereal extracts were washed with water and dried over MgSO~. Ether was evaporated and chromatography of the residue on alumina with hexane as the eluent gave 2.8 g of previously reported allene (I), nD 2~ 1.6370. P~{ spectrum (6, ppm): 6.94 t (IH, HA) , 5.43 d (2H, HB), 4JHAHB 6.6 Hz, 6.94 t (IH, HS), 6.26 d (2H, H 3, H4), 7.36 m (5H, Ph). IR spectrum (~, cm-1): 1950 (C-C-~), 1604, 1500 (Ph), 1475, 1380 (pyrrole ring), 1314 (C-N). The elemental analysis corresponded to the proposed chemical formula. In light of the availability of 1,2,3-trichloropropane, which is produced in large amounts as a by-product in the production of epichlorohydrin, this simple and efficient method for allenylation under mild conditions holds promise for use in the synthesis of various heterocyclic compounds with a labile hydrogen atom. Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2161- 2162, September, 1991. Original article submitted April 19, 1991o 1918 0568-5230/91/4009-1918512o50 1992 Plenum Publishing Corporation

Upload: o-a-tarasova

Post on 13-Aug-2016

218 views

Category:

Documents

1 download

Report

Download

Embed Size (px):

TRANSCRIPT

N-ALLENYLATION OF PYRROLES USING 1,2,3-TRICHLOROPROPANE

O. A. Tarasova, T. L. Markova, and B. A. Trofimov UDC 542.91:547.748:547.412.614

We have found that 1,2,3-trichloropropane is an efficient allenylating agent for pyrroles in the KOH/DMSO superbase system. Thus, l-propadienyl-2-phenylpyrrole (I) was ob- tained in 62% yield directly from 2-phenylpyrrole. The double dehydrochlorination, nucleo- philic substitution of the chlorine atom by the pyrrolate anion, and prototropic isomeriza- tion of intermediate l-(2-propynyl)-2-phenylpyrrole to an allene were carried out in a sin- gle preparative step with almost 100% selectivity.

II,~ H 4 \ /

CICH,CHClCtt~Cl / \ / ~- / \ , ' \ Ph N KOll/ DMS0 Ph N H-'

H t U IIAC=C=CtI 2 (I)

A sample of 5.53 g 1,2,3-trichloropropane was added over i0 min to a mixture of 3.56 g 2-phenylpyrrole, 11.2 g KOH (subjected to prior roasting at 500~ for 4 h), and 50 ml dry DMSO (containing 0.2% H20). Heat was evolved and the temperature rose to 40~ The mixture was then heated for an additional 20 min at 40~ and I00 ml water was added. The reaction mixture was extracted with ether. The ethereal extracts were washed with water and dried over MgSO~. Ether was evaporated and chromatography of the residue on alumina with hexane as the eluent gave 2.8 g of previously reported allene (I), nD 2~ 1.6370. P~{ spectrum (6, ppm): 6.94 t (IH, HA) , 5.43 d (2H, HB), 4JHAHB 6.6 Hz, 6.94 t (IH, HS), 6.26 d (2H, H 3, H4),

7.36 m (5H, Ph). IR spectrum (~, cm-1): 1950 (C-C-~), 1604, 1500 (Ph), 1475, 1380 (pyrrole ring), 1314 (C-N). The elemental analysis corresponded to the proposed chemical formula.

In light of the availability of 1,2,3-trichloropropane, which is produced in large amounts as a by-product in the production of epichlorohydrin, this simple and efficient method for allenylation under mild conditions holds promise for use in the synthesis of various heterocyclic compounds with a labile hydrogen atom.

Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2161- 2162, September, 1991. Original article submitted April 19, 1991o

1918 0568-5230/91/4009-1918512o50 �9 1992 Plenum Publishing Corporation

A novel synthetic methodology for pyrroles from nitrodienes ......FULL PAPER A novel synthetic methodology for pyrroles from nitrodienes Mohamed A. EL-Atawy,[a,b] Francesco Ferretti,[a]

Estación del tren A North Central Texas College: sur 1 ......1,2,3 Conexiones 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 Hospital Lugar de interés 1,2,3 Referencias NORTH NORTE Horarios de NCTC

#1,2,3 Francisco Nieto-Lopez#1,2,3 Cristina Sánchez

An expedient synthesis of poly-substituted pyrroles from γ ...szolcsanyi/education/files/Chemia...An expedient synthesis of poly-substituted pyrroles from c-ketonitriles via indium-mediated

Synthesis of Pyrroles and Indoles Carbonyl condensations (c.f. chapt. 3) - Pyrroles Strategy a; Paal-Knorr synth. Not useful for indoles

U.S. Department of the Interior Occurrence of Volatile ... · 1,2-Dibromoethane 1,2,3-Trichloropropane tert-Butylbenzene 2-Propenenitrile Hexachlorobutadiene Methyl acrylate Bromoethene

CICAD 56 - 123-Trichloropropane - Version 3 - who.int · 1,2,3-Trichloropropane 1 FOREWORD Concise International Chemical Assessment Documents (CICADs) are the latest in a family

Next Hurdle: 1,2,3-Trichloropropane - CA-NV AWWA · A value of 0.1 lb GAC / 1,000 gallons has been assumed pending a site specific water quality evaluation and testing Chemical Molecular

1,2,3 1,2,3,* and Miguel Yus 3,

Pd-Mediated new synthesis of pyrroles: Their evalution as ...Pd-Mediated new synthesis of pyrroles: Their evalution as potential inhibitors of phosphodiesterase 4 G. Rajeshwar Reddy,

Recent approaches in the organocatalytic synthesis of pyrroles