M. M.-C. Lo, G. C. Fu / Tetrahedron 57 (2001) 2621±2634
2627
13C NMR (126 MHz, CDCl3): d 28.2, 35.1, 50.1, 69.6, 81.6,
84.0, 127.0, 127.5, 128.8, 142.1, 172.1.
3.6.3. Table 1, entry 3. Run 1: 91:9 trans/cis; trans
ee97% ee (major enantiomer: 2S,3R). Run 2 (with (S,S)-
2, (S)-oxetane, (d)-menthyl diazoacetate): 90:10 trans/cis;
trans ee97% ee (major enantiomer: 2R,3S).
t-Butyl (2S,3S)-3-phenyltetrahydrofuran-2-carboxylate.
13C NMR (126 MHz, C6D6): d 27.7, 31.8, 48.1, 68.9,
81.2, 81.8, 127.1, 128.4, 128.6, 139.5, 170.2.
(d)-Menthyl (2R,3S)-3-phenyltetrahydrofuran-2-carb-
1
oxylate. H NMR (500 MHz, C6D6): d 0.59 (dq, 1H, J
3.8, 12.7 Hz), 0.75 (d, 3H, J6.4 Hz), 0.79 (d, 3H, J
4.9 Hz), 0.80 (d, 3H, J4.6 Hz), 0.7±0.85 (m, 1H), 0.89
(q, 1H, J11.7 Hz), 1.1±1.2 (m, 1H), 1.26 (tdd, 1H, J
3.1, 11.0, 12.4 Hz), 1.36±1.44 (m, 2H), 1.71 (qd, 1H, J
7.8, 12.4 Hz), 1.93±2.08 (m, 3H), 3.56 (dt, 1H, J5.8,
7.6 Hz), 3.94 (dt, 1H, J4.3, 8.1 Hz), 4.08 (dt, 1H, J7.0,
8.2 Hz), 4.60 (d, 1H, J5.8 Hz), 4.93 (dt, 1H, J4.4,
10.9 Hz), 7.08 (tt, 1H, J1.8, 6.9 Hz), 7.09±7.15 (m, 4H).
13C NMR (126 MHz, C6D6): d 16.8, 21.2, 22.5, 23.9, 26.8,
31.8, 34.7, 35.5, 41.5, 47.5, 50.5, 69.8, 74.8, 84.5, 127.4,
127.9, 129.3, 143.0, 172.5. IR (neat): 3063 (w), 3029 (w),
2954 (s), 2870 (s), 1743 (s), 1604 (w), 1494 (m), 1455 (s),
1370 (m), 1264 (s), 1194 (s), 1100 (s), 986 (m), 758 (m), 700
(m) cm21. HRMS (FAB, m/z): Calcd for C21H30O3:
3.6. General procedureÐTable 1
A solution of (R,R)-2 (4.4 mg, 8.4 mmol) in EtOAc (2 mL)
was added to CuOTf´0.5C6H6 (1.8 mg, 7.2 mmol) and
stirred for 30 min. The catalyst solution was then ®ltered
through an acrodisc to afford an orange solution. Half of this
solution was transferred to a ¯ask containing (R)-2-phenyl-
oxetane (48.7 mg, 0.363 mmol), and EtOAc was added until
the total volume was 2.5 mL. The solution was stirred for
5 min in a water bath maintained at 208C, and then a solu-
tion of the diazo ester (0.48 mmol) in EtOAc (1 mL) was
added over 5 min to the reaction mixture. After 30 min, the
reaction mixture was ®ltered through a plug of silica gel
(Et2O as the eluant) to afford the crude product.
330.2195 (M1). Found: 330.2202. [a]20 2388 (c1.10,
D
EtOH, .99.5% de).
3.6.1. Table 1, entry 1. Run 1: 81:19 trans/cis; trans
ee91% ee (major enantiomer: 2S,3R). Run 2 (with (S,S)-
2, (S)-oxetane): 82:18 trans/cis; trans ee92% ee (major
enantiomer: 2R,3S).
3.6.4. Table 1, entry 4. Run 1: 90:10 trans/cis; trans
ee97% ee (major enantiomer: 2S,3R). Run 2 (with (S,S)-
2, (S)-oxetane): 90:10 trans/cis; trans ee97% ee (major
enantiomer: 2R,3S).
Ethyl (2R,3S)-3-phenyltetrahydrofuran-2-carboxylate.
1H NMR (500 MHz, C6D6): d 0.85 (t, 3H, J7.2 Hz),
1.68 (qd, 1H, J7.8, 12.4 Hz), 1.99 (dtd, 1H, J4.6, 7.5,
12.2 Hz), 3.45 (dt, 1H, J6.0, 7.7 Hz), 3.90 (m, 3H), 4.02
(dt, 1H, J6.7, 8.2 Hz), 4.52 (d, 1H, J5.8 Hz), 7.00±7.06
(m, 1H), 7.08 (m, 4H). 13C NMR (126 MHz, CDCl3): d
14.4, 35.1, 49.8, 61.2, 69.7, 83.6, 127.1, 127.4, 128.9,
141.9, 172.9. IR (neat): 3030 (w), 2979 (m), 2878 (m),
1747 (s), 1603 (w), 1493 (w), 1455 (w), 1266 (m), 1192
(s), 1098 (s), 759 (m), 700 (s) cm21. HRMS (FAB, m/z):
Calcd for C13H16O3: 220.1099 (M1). Found: 220.1105.
3.6.5. Table 1, entry 5. Run 1: 95:5 trans/cis; trans
ee98% ee (major enantiomer: 2S,3R). Run 2 (with (S,S)-
2, (S)-oxetane): 95:5 trans/cis; trans ee98% (major enan-
tiomer: 2R,3S).
10,10-Dicyclohexylethyl (2R,3S)-3-phenyltetrahydrofuran-
2-carboxylate. H NMR (500 MHz, C6D6): d 0.9±1.2 (m,
1
10H), 1.43 (s, 3H), 1.5±1.8 (m, 11H), 1.85 (t qnt, 2H, J2.8,
11.6 Hz), 2.03 (dddd, 1H, J4.3, 6.7, 7.6, 11.9 Hz), 3.54 (dt,
1H, J6.4, 7.9 Hz), 3.93 (dt, 1H, J4.0, 8.1 Hz), 4.04 (dt,
1H, J6.7, 8.5 Hz), 4.51 (d, 1H, J6.4 Hz), 7.02±7.06 (m,
1H), 7.10± 7.16 (m, 4H). 13C NMR (125 MHz, C6D6): d
19.8, 27.2, 27.5, 27.6, 28.2, 28.2, 28.6, 28.7, 36.0, 45.5,
50.6, 69.8, 85.2, 91.1, 127.3, 128.0, 129.2, 142.9, 172.2.
IR (neat): 2929 (s), 2852 (s), 1742 (s), 1449 (s), 1190 (s),
1100 (s), 755 (m), 700 (s) cm21. HRMS (FAB, m/z):
Calcd for C25H36O3: 385.2743 (M1H1). Found: 385.2732.
[a]20 2998 (c0.99, EtOH, 92% ee).
D
3.6.2. Table 1, entry 2. Run 1: 90:10 trans/cis; trans
ee95% ee (major enantiomer: 2S,3R). Run 2 (with (S,S)-
2, (S)-oxetane, (l)-menthyl diazoacetate): 90:10 trans/cis;
trans ee95% ee (major enantiomer: 2R,3S).
(l)-Menthyl (2R,3S)-3-phenyltetrahydrofuran-2-carboxyl-
[a]20 2638 (c1.00, EtOH, 98% ee).
1
ate. H NMR (500 MHz, C6D6): d 0.58 (dq, 1H, J3.9,
D
12.7 Hz), 0.72 (d, 3H, J6.4 Hz), 0.76 (d, 3H, J4.9 Hz),
0.78 (d, 3H, J4.9 Hz), 0.75±0.82 (m, 1H), 0.86 (q, 1H,
J11.6 Hz), 1.08±1.18 (m, 1H), 1.21 (tdd, 1H, J3.1, 11.0,
12.3 Hz), 1.36±1.44 (m, 2H), 1.71 (ddd, 1H, J8.5, 12.2,
16.5 Hz), 1.77 (dtd, 1H, J2.8, 7.2, 14.4 Hz), 1.98±2.05 (m,
2H), 3.53 (dt, 1H, J6.6, 8.0 Hz), 3.94 (dt, 1H, J3.8,
8.0 Hz), 4.06 (dt, J6.6 Hz, 1H, 8.5), 4.58 (d, 1H, J
6.4 Hz), 4.85 (dt, 1H, J4.3, 10.8 Hz), 7.0±7.06 (m, 1H),
7.10±7.14 (m, 4H). 13C NMR (126 MHz, C6D6): d 16.6,
21.2, 22.4, 23.8, 26.5, 31.8, 34.7, 36.1, 41.4, 47.4, 51.0,
70.0, 74.9, 84.6, 127.4, 127.9, 129.3, 142.4, 172.8. IR
(neat): 3063 (w), 3029 (w), 2954 (s), 2870 (s), 1742 (s),
1604 (w), 1494 (m), 1455 (s), 1371 (m), 1265 (m), 1193
(s), 1099 (s), 986 (m), 758 (m), 700 (s) cm21. HRMS (FAB,
m/z): Calcd for C21H30O3: 330.2195 (M1). Found: 330.2205.
3.7. General procedureÐTables 2 and 3
A solution of (R,R)-2 (4.7 mg, 8.9 mmol) in EtOAc (1 mL)
was added to CuOTf´0.5C6H6 (1.9 mg, 7.5 mmol) and
stirred for 1 h. The catalyst solution was then ®ltered
through an acrodisc to afford an orange solution. Half of
this solution was added to a ¯ask containing the oxetane
(0.39 mmol), and EtOAc was added until the total volume
was 0.8 mL. The solution was stirred for 5 min in a water
bath maintained at 208C, and then a solution of the diazo-
acetate (170 mg, 0.62 mmol) in EtOAc (1 mL) was added to
the reaction mixture in four batches over 3 h. After one
additional hour, the reaction mixture was ®ltered through
a plug of silica gel (Et2O as the eluant).
[a]20 21358 (c1.29, EtOH, 96% de).
D