Phosgenation Reactions - Phosgenations - page 250

Tab. 4.26. Reaction of DSC with various alcohols R-OH 959 forming mixed succinimidyl
carbonates 960 [677].

Alcohol R-OH 959 Mixed succinimidyl

carbonate 960

Yield (%)

fluoren-9-ylmethanol Fmoc-OSu 82

benzyl alcohol Z-OSu 81

2-chlorobenzyl alcohol 2ClZ-OSu 79

2,2,2-trichloroethanol Troc-OSu 80

2-trimethylsilylethanol TEOC-OSu 81

cholesterol ChOC-OSu 78

tert-amyl alcohol Aoc-OSu 80

tert-butyl alcohol Boc-OSu 25

General procedure. Reaction of DSC with alcohols 959 forming 960 [677]: To a solution
of the alcohol 959 (1 mmol) in dry acetonitrile (4 mL), DSC (for a preparation, see
Section 4.3.3.4) (1.5 mmol) and triethylamine (3 mmol) were added. The clear so-
lution was stirred at room temperature for 8-10 h. After completion of the reac-
tion, the solvent was evaporated under reduced pressure. The residue was dis-
solved in dichloromethane (50 mL), and the solution was washed with 5% aq.
NaHCO 3 solution (2

8 mL), dried (Na 2 SO 4 ), and concen-
trated to dryness. The residue was crystallized from ethyl acetate/light petroleum
(bp 40-60 C) to afford 960 (for yields, see Table 4.26).
DSC is employed as a coupling agent in the synthesis of thiophospholipids
[678]. The attachment of biomembranes to solid supports is important in a variety
of areas, from fundamental studies of bilayer structure and function to the creation
of biocompatible surfaces and biosensors. DSC has been used to couple diacyl-
glycerophosphatidylethanolamine with o-hydroxypolyethyleneoxydisulfide. The re-
sultant thiophospholipids can be used for anchoring biomembranes to gold sur-
faces. The reaction of DSC with 8-benzylthio-3,6-dioxaoctanol 961 affords 962 in
79% yield [678].

8 mL) and water (2

Typical procedure. N-(8-Benzylthio-3,6-dioxaoctyloxycarbonyloxy)succinimide 962 [678]:
To a stirred solution of 8-benzylthio-3,6-dioxaoctanol 961 (0.52 g, 2.03 mmol) in dry
MeCN (5 mL) at room temperature were added DSC (for a preparation, see Section
4.3.3.4) (1.04 g, 4.06 mmol) and triethylamine (0.62 g, 0.85 mL, 6.09 mmol). The
resulting mixture was stirred at room temperature for 4 h and then the solvent was
removed in vacuo. The product was separated by column chromatography on sil-
ica gel (ethyl acetate/petroleum ether, 2:1) to give N-(8-benzylthio-3,6-dioxaoctyl-
oxycarbonyloxy)succinimide 962 (0.64 g, 1.61 mmol, 79%) as a viscous, pale-yellow
oil; MS (EI): m/z ¼ 396 [M þ 1].

Dimethyl carbonate (DMC)
Dimethyl carbonate (DMC) has been employed as a carbonyl transfer agent to
form a 5,6-cyclocarbonate on 3-O-benzyl-1,2-O-isopropylidene-a-d-glucofuranose