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In-Depth Information
is immediately methoxycarbonylated with methyl chloroformate resulting in the
carbonate 833 (yield 79%), which is removed by catalytic reduction to compound
834 [614].
Typical procedure. (1E,3S)-3-tert-Butyldimethylsilyloxy-2-methyl-6-trimethylsilyl-1-(2-
methyl-1,3-thiazol-4-yl)-1-hexen-5-yne 834 (via carbonate 833) [614]:
Trimethylsilyl-
acetylene (198
m
L, 1.4 mmol) was dissolved in THF (5 mL) and the solution was
78
C. Butyllithium (903
cooled to
L, 1.55 m in hexane, 1.4 mmol) was added,
and the reaction mixture was stirred at the same temperature for 20 min. Then, a
solution of aldehyde 832 (218 mg, 0.7 mmol) in THF (1 mL) was added, followed,
after 40 min, by methyl chloroformate (216
m
L, 2.8 mmol). The resulting mixture
was stirred for a further 30 min. Saturated aqueous NaHCO
3
solution (30 mL) was
then added, followed by EtOAc (30 mL). The organic layer was separated, and the
aqueous phase was further extracted with EtOAc (2
m
30 mL). The combined or-
ganic layers were washed with brine, dried (Na
2
SO
4
), and concentrated; the resi-
due was purified by flash chromatography on silica gel (EtOAc/hexane, 1:10) to
