A Route to Carbasugar Analogues - Jonathan Clayden - The ...

Experimental for chapter 3.1
101b data as enantiopure (vide infra) Chiral HPLC: Pircle Covalent (R,R) Whelk-O1
column, 10% IPA in hexane, 1ml/ min: 50% - 11.3 min, 50% - 20.0 min.
Synthesis of (4R, 5R)-2-(4-methoxyphenyl)-4,5-diphenyloxazoline (101b)
HO
O
Ph
NH
Ph
DIC, Cu(OTf) 2
Ph
O
N
Ph
Δ
OMe OMe
Reflux:General procedure 2 was used with benzamide (20.0 mg, 57.6 mmol), DIC
(8.96 cm 3 , 57.6 mmol), Cu(OTf) 2 (1.25 g, 3.50 mmol), dioxane (175 cm 3 ) and heated
under reflux for 12 hr at 120 °C. Flash chromatography (9:1 to 4:1 petrol:EtOAc)
yielded oxazoline 101b (8.67 g, 46%) as colourless needles.
Microwave:General procedure 2 was used with benzamide (700 mg, 2.01 mmol), DIC
(0.31 cm 3 , 2.01 mmol), Cu(OTf) 2 (44 mg, 0.12 mmol), THF (7 cm 3 ) and heated under
microwave irradiation for 30 min. at 140 °C. Flash chromatography (9:1 to 4:1
petrol:EtOAc) yielded oxazoline 101b (661 mg, 72%) as colourless needles.
Ph
Ph
Ph
Ph
Ph
O
N
Ph
SiO 2 slurry, CH 2 Cl 2
O
1
N
O
N
2
OMe
3
4
OMe
OMe
101b 109b
An excess of silica was added to a stirred solution of aziridine 100b (1.38 g, 4.2 mmol)
in CH 2 Cl 2 (20 cm 3 ) and stirred for 8 days. The mixture was filtered, concentrated
under vacuum and purified by flash chromatography (9:1 to 3:1 petrol:EtOAc) to yield
oxazoline 101b (800 mg, 58%) as clear cubic crystals, and its diastereomeric oxazoline
109b (7 mg, 1%).
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