General Remarks. General chemicals were used as received. All manipulations were carried out under an argon atmosphere unless otherwise noted. Solvents were purified by MBRAUN MB-SPS system. Preparative thin-layer chromatography (PTLC) was performed using Merck silica gel 60 PF 254 . Gel permeation liquid chromatography (GPLC) was performed using LC-918 or LC-908 with JAIGEL 1H+2H columns (Japan Analytical Industry) using chloroform or toluene as solvents, respectively. NMR spectra were

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... by a JEOL AL-400 spectrometer ( 1 H, 400 MHz; 13 C, 100 MHz). Chemical shifts are reported in δ. 1 H NMR spectra are referenced to residual protons in deuterated solvent; 13 C NMR spectra are referenced to carbon-13 in the deuterated solvent. Low resolution mass spectra were obtained with a JEOL JMS-700P using m-nitrobenzyl alcohol as a matrix. High resolution mass spectra were recorded by a JEOL JMS-700P using PEG600 or Ultramark® as internal standards. Infrared spectra were recorded with a JASCO Irtron IRT-30. All melting points were measured with a Yanaco MP-S3 and uncorrected. Elemental analyses were performed by the