points were
determined in a Cole–Palmer apparatus and are uncorrected.
TLC was performed on Merck aluminum-backed plates coated with 0.2
mm thick silica gel 60 F254. Column chromatography was
carried out on silica gel 70–230 or 230–400 mesh from
Sigma-Aldrich, eluting with mixtures of increasing polarity of n-hexane/methylene chloride or n-hexane/ethyl
acetate. Electronic impact mass spectra (EIMS) were obtained in a
JEOL JMS-AX505HA spectrometer with an ionization potential of 70 eV.
DART and high-resolution electro-spray ionization mass spectra (HRESIMS)
were obtained in an AccuTOF JMS-T100LC spectrometer. IR spectra were
recorded using a Bruker Tensor 750 FT-IR spectrophotometer. The specific
rotation was determined on a PerkinElmer 343 polarimeter using chloroform
as the solvent and sodium D line as the source of light. 1H, 13C, and bidimensional NMR spectra were recorded in
Bruker Avance III (400/100 MHz), Bruker Fourier (300/75 MHz), and
Jeol Eclipse (300/75 MHz). HPLC was carried out in a Thermo Scientific
Ultimate 3000 chromatographer using analytical C18 (5 μm, 100
Å, 15 × 4.6 mm, 5 μm). The HPLC-grade solvents employed
(iPrOH, MeOH, MeCN) were from the brand Fermont.
The X-ray data were collected on a Bruker APEX II Duo diffractometer.