G1969a instrumentation

All reactions that involved
compounds sensitive to air and/or moisture were carried out under
a dry nitrogen atmosphere using freshly dried solvents and standard
Schlenk line and glovebox techniques. All chemicals were purchased
from commercial sources. Toluene, hexanes, and THF were distilled
under nitrogen from Na/benzophenone. CDCl₃ was dried over
CaH₂, distilled, and degassed prior to use. rac-LA was recrystallized from dry toluene, sublimed under vacuum, and
stored under a dry nitrogen atmosphere.
NMR spectra were recorded
on a Bruker AVANCE-500 NMR spectrometer (¹H, and ¹³C) and referenced to the residual solvent peak. J values are given in Hz. Gel permeation chromatography (GPC) analysis
was performed on a Varian Prostar instrument, using a PLgel 5 μm
Mixed-D column, a Prostar 355 RI detector, and THF as eluent at a
flow rate of 1 mL/min (20 °C). Polystyrene standards were used
for calibration. Matrix-assisted laser desorption/ionization time-of-flight
mass spectrometry (MALDI-TOF MS) spectra were obtained on Applied
Biosystems/MD SCIEX 4800 equipment using α-cyano-4-hydroxycinnamic
acid as a matrix and 5 mM sodium acetate as an ionization agent. The
HR-MS was performed using high-resolution time-of-flight G1969A instrumentation
(Agilent). The optical rotation was measured on a Jasco P-2000 polarimeter
with a 589 nm light source at 23 °C.

NMR spectra were recorded on a Bruker
AVANCE-500 NMR spectrometer (¹H and ¹³C). GPC
analysis was performed on a Varian Prostar, using a PLgel 5 μm
Mixed-D column, a Prostar 355 RI detector, and tetrahydrofuran as
the eluent at a flow rate of 1 mL/min (20 °C). Polystyrene standards
were used for calibration. The HR-MS (ESI-TOF) was performed on a
high-resolution time of flight G1969A instrumentation (Agilent) using
2.5 mM ammonium acetate as an ionizing agent. The DSC data were collected
on a PerkinElmer Pyris DSC using 10.0 °C/min heating rate with
20 mL/min nitrogen flow. The FT-IR spectrum was recorded on a PerkinElmer
Spectrum 400 FT-IR spectrophotometer.