PDF《pure heterocycles》

S1 Catalytic conversion of lactide to optically pure heterocycles Shinji Tsunoi, Hiroki Takahashi, Yugo Takano, Aritomo Okamura, Ikuya Shibata* Research Center for Environmental Preservation, Osaka University, 2-4 Yamadaoka, Suita, Osaka 565-0871, Japan.

Supporting Information General S2 Representative procedure S2 Analytical data S6 NMR charts S14 S2 General Analysis. IR spectra were recorded as thin film on a Nocolet Magna-750 spectrometer. All

1 H and

13 C NMR spectra were recorded with a JEOL JMTC-400/54/SS (400 and

100 MHz, respectively) in deuteriochloroform (CDCl3) containing 0.03% (w/v) of tetramethylsilane as internal standard. Mass spectra were recorded on a JEOL JMS-DS-303 spectrometer. Specific rotation was measured with DIP-181 made by JASCO in CHCl3. PLC was performed TOSOH CCPS-UV8020 system using Daicel CHIRALPAK IA (0.46 cmD x 25cmL) detected at

254 nm eluted by 1.0 mL/min Hexane/CHCl3=50/50. Flash column chromatography was performed by Yamazen YFLC-AI-580 using Hi-Flash Silica gel 2L Hi-Flash Column 20-3-mL/min eluted by Hexane/EtOAc with gradation mode changing from 9/1 to 3/7. Purification of products by recycle GPC system was performed by Japan Analytical Industry Co., Ltd. LC-908 eluted by CHCl3. Materials. Di-n-butyltin dimethoxide [n Bu2Sn(OMe)2] was prepared according to the reported method using n Bu2SnO and dimethyl carbonate (A. G. Davies, D. C. Kleinschmidt, P. R. Palan, S. C. Vasishtha, J. Chem. Soc. (C) 1971, 3972-3975.). Sn(OCOC7H17)2 was purchased from Nakarai Tesque Co., Ltd. Substrates such as methyl glycolate 1a (Tokyo Kasei), glycolide 1b (Sigma), lactide 1c (Aldrich) are commercially available. Phenyl lactide 1d was prepared as an optically pure form by dimerization of phenyl lactic acid (Bacem Co., Ltd.) according to the known method (T. L. Simmons, G. L. Baker, Biomacromolecules 2001, 2, 658-663.). All reactions were carried out under dry nitrogen. Representative procedure Representative procedure for the preparation of 2-oxazolidinone under microwave irradiation. Microwave assisted reactions were carried out using a focused microwave unit (CEM Discover microwave). The instrument consists of a continuous focused microwave power delivery system with operator selectable power output from 0-300 W. In all experiments, a constant power was applied to ensure reproducibility. Reactions were performed in glass vessels (10 mL) sealed with a septum. Pressure experiment is accomplished by a non-invasive sensor integrated into the cavity lid, which measures the deformation of the Teflon seal of the vessels (maximal

20 bar). Temperature controlled is achieved by means of an IR sensor and the indicated temperature corresponds to the maximal temperature reached during each experiment. The specified reaction time corresponds to the total irradiation time. Efficient cooling is accomplished by means of a pressurized air during the entire experiment. S3 Reaction of methyl glycolate (1a) with isocyanate catalyzed by Bu2Sn(OMe)2 (Table 1, entry 5). A

5 mL of vial was dried by flame under reduced pressure. After nitrogen was filled, Bu2Sn(OMe)2 (0.0295 g, 0.1 mmol), MeCN (1.0 mL), methyl glycolate (1a) (0.09g, 1.0 mmol) and butyl isocyanate (0.099g, 1.0 mmol) were added. The mixture was stirred at rt for

3 h. After the reaction, the mixture was quenched by H2O (0.5 mL), and the layers were quickly separated. The aqueous phase was further extracted with ether, and the combined extracts were dried over sodium sulfate and concentrated. The yield and product ratio 2a/2a'

was determined by