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Chapter 2
Synthesis of substituted pyrimidines via Wittig
2.10 Experimental section
Thin-layer chromatography was accomplished on 0.2-mm precoated plates of
silica gel G60 F 254 (Merck). Visualization was made with UV light (254 and 365nm)
or with an iodine vapor. IR spectra were recorded on a FTIR-8400 spectrophotometer
using DRS prob. 1 H (300 MHz), 1 H (400 MHz), 13 C (100 MHz) and 13 C (75 MHz)
NMR spectra were recorded on a Bruker AVANCE II spectrometer in CDCl 3 and
DMSO. Chemical shifts are expressed in δ ppm downfield from TMS as an internal
standard. Mass spectra were determined using direct inlet probe on a GCMS-QP 2010
mass spectrometer (Shimadzu). Solvents were evaporated with a BUCHI rotary
evaporator. Melting points were measured in open capillaries and are uncorrected.
Synthesis of (2-chloro-4-(4-fluorophenyl)-6-isopropylpyrimidin-5-yl)
methanol. (INT-01)
To a solution of ASM-03e (0.003 mole) in toluene (100 mL) at 0 o C was
added drop wise a 20% solution of diisobutylaluminium hydride (DIBAL) in toluene
(85 mL). The reaction mixture was further stirred for 2-3 h. at 0 o C. The progress of
reaction was monitored by thin layer chromatography. After completion, the reaction
mixture was quenched with saturated ice cold hydrochloric acid. The toluene layer
was washed with water and brine. The organic layer was separated, dried over
anhydrous sodium sulfate and filtered. The filtrate was dried under vacuum. The solid
product was purified by stirring in hexane or diisopropylether (DIPE) to give
analytically pure product INT-01 with 85% yield.
Synthesis of triphenyl[2-chloro-{4-(4-flourophenyl)-6-isopropylpyrimidin-5-ylmethyl}phosphonium]bromide.
(INT-02)
A solution of 2-chloro-4-(4-fluorophenyl)-6-isopropylpyrimidin-5-yl)
methanol (INT-01, 16mmol) in MDC (50 mL) was cooled to 0-5 o C. Phosphorus
tribromide (13mmol) was slowly added in to the reaction mixture at 0-5 o C and stirred
for 2-3 h. The progress of reaction was monitored by thin layer chromatography.
After completion, the reaction mixture was washed with 10% sodium bicarbonate
solution and sodium thiosulphate solution. The organic layer was separated, dried
over anhydrous sodium sulfate and filtered. The filtrate was evaporated to dryness
under vacuo.
Department of Chemistry, Saurashtra university, Rajkot-360005 64