Pt-Catalyzed Diyne Cyclization/Hydrosilylation
J . Org. Chem., Vol. 67, No. 9, 2002 2787
vacuum. Chromatography of the residue (Al2O3; hexanes-
EtOAc ) 25:1) gave (E)-3 (134 mg, 81%, 95% E).
Diels-Ald er Ad d u ct of (Z)-3 a n d N-ter t-Bu tylm a leim -
id e (46). 1H NMR: δ 3.69 (s, 3 H), 3.66 (s, 3 H), 2.93-2.99
(m, 3 H), 2.82-2.86 (m, 3 H), 2.42-2.46 (m, 1 H), 2.21-2.31
(m, 2 H), 1.49 (s, 9 H), 1.20-1.35 (m, 12 H), 0.87 (t, 7.0 Hz, 9
H), 0.52-0.56 (m, 6 H). 13C{1H} NMR: δ 181.9, 172.7, 134.2,
127.6, 58.0, 52.9, 44.9, 43.9, 40.8, 40.0, 28.4, 27.1, 26.1, 25.5,
25.0, 13.9, 12.2. IR (neat, cm-1): 2985, 1740, 1447, 1373, 1241,
1098, 1047, 938, 787. HRMS calcd (found) for C27H35NO6Si:
561.3486 (561.3483).
Isom er iza tion of (Z)-42. A solution (Z)-42 (72 mg, 0.14
mmol) and iodine (12 mg, 0.047 mmol) in benzene (1.5 mL)
was stirred at room temperature for 6.5 h, quenched with 10%
aqueous sodium thiosulfate (5 mL), and extracted with ethyl
acetate (2 × 100 mL). The combined organic fractions were
washed with sodium thiosulfate solution (2 × 75 mL), dried
(MgSO4), and concentrated under vacuum. Chromatography
of the residue (Al2O3; hexanes-EtOAc ) 30:1 f 3:1) gave 42
(51 mg, 71%) as a 2:1 mixture of E:Z isomers.
Diels-Ald er Ad d u ct of (Z)-3 a n d N-Meth ylm a leim id e
1
(47). White solid, mp 105-106 °C. H NMR: δ 3.68 (s, 3 H),
F or (E)-42: 1H NMR: δ 5.68 (s, 1 H), 5.21 (s, 1 H), 5.15 (d,
J ) 1.6 Hz, 1 H), 5.00 (d, J ) 2.0 Hz, 1 H), 4.80 (d, J ) 2.0 Hz,
1 H), 4.73 (d, J ) 1.2 Hz, 1 H), 4.11-4.24 (m, 8 H), 3.70 (m, 1
H), 2.95-3.14 (m, 2 H), 2.61-2.85 (m, 1 H), 1.21-1.29 (m, 12
H), 0.85-1.00 (m, 9 H), 0.69-0.78 (m, 3 H), 0.51-0.62 (m, 3
H). 13C{1H} NMR. δ 169.7, 151.8, 145.8, 134.0, 125.2, 123.2,
114.2, 113.0, 62.3, 62.1, 61.9, 58.8, 39.3, 38.2, 37.4, 35.4, 15.5,
14.2, 8.1, 7.9, 5.2, 4.8, 4.4.
3.65 (s, 3 H), 3.11 (td, J ) 1.6, 8.8 Hz, 1 H), 3.00 (d, J ) 8.8
Hz, 1 H), 2.95 (m, 1 H), 2.92 (s, 3 H), 2.78-2.85 (m, 2 H), 2.46-
2.51 (m, 2 H), 2.36 (s, 1 H), 2.24-2.30 (m, 1 H), 0.96 (t, J )
8.0 Hz, 9 H), 0.59 (q, J ) 8.0 Hz, 6 H). 13C{1H} NMR: δ 181.2,
180.6, 172.8, 172.4, 134.0, 127.6, 58.2, 53.1, 44.7, 43.8, 40.6,
39.9, 25.7, 24.7, 24.6, 7.7, 3.6. IR (neat, cm-1): 2953, 2876,
1775, 1735, 1700, 1434, 1383, 1336, 1262, 1198, 1157, 1122,
1071, 1042, 994, 730. Anal. Calcd (found) for C22H33NO6Si: C,
60.66 (60.74); H 7.64 (7.73); N 3.22 (3.18).
3,3-Dica r b om et h oxy-1-m et h yl-5-m et h ylen ecyclop en -
ten e (43).37 A solution of (Z)-3 (120 mg, 0.37 mmol), iodine
(11 mg), and water (0.1 mL) in benzene (3 mL) was stirred at
80 °C for 6 h and concentrated under vacuum. Chromatogra-
phy of the residue (Al2O3; hexanes-EtOAc ) 25:1) gave 43
Diels-Ald er Ad d u ct of (Z)-3 a n d Ben zoqu in on e (48).
1
Yellow solid. H NMR: δ 6.64 (s, J ) 10.8 Hz, 1 H), 6.56 (d, J
) 10.4 Hz, 1 H), 3.14-3.17 (m, 2 H), 3.08-3.14 (m, 1 H), 2.84-
2.93 (m, 2 H), 2.74-2.78 (m, 1 H), 2.57 (s, 1 H), 2.22-2.24 (m,
1 H), 1.97-2.04 (m, 1 H), 0.93 (t, J ) 8.0 Hz, 1 H), 0.58 (q, J
) 8.0 Hz, 6 H). 13C {1H} NMR: δ 201.9, 198.6, 172.9, 172.5,
140.2, 138.2, 133.4, 125.9, 58.1, 53.2, 48.7, 47.6, 44.4, 43.4, 27.1,
21.7, 7.8, 4.1. IR (neat, cm-1): 1733, 1653, 1638, 1264, 1079,
1044, 877. Anal. Calcd (found) for C23H32O6Si: C, 63.86 (63.80);
H, 7.46 (7.57).
1
(60 mg, 77%). H NMR: δ 5.89 (s, 1 H), 4.91-4.88 (m, 2 H),
3.71 (s, 6 H), 3.16 (t, J ) 2.0 Hz, 2 H). 13C{1H} NMR: δ 171.6,
151.3, 144.7, 131.3, 104.1, 63.7, 53.2, 38.3, 12.9.
1,1-Dica r b om e t h oxy-3,4-d im e t h yle n e cyclop e n t a n e
(44).38 A solution of (Z)-3 (108 mg, 0.33 mmol) and trifluoro-
acetic acid (60 µL, 0.77 mmol) in CH2Cl2 (1 mL) was stirred at
0 °C for 35 min, quenched with Na2CO3 (5 mL), and extracted
with ethyl acetate (3 × 50 mL). The combined organic extracts
were dried (MgSO4) and concentrated under vacuum. Chro-
matography of the residue (SiO2; hexanes-EtOAc ) 25:1) gave
44 (44 mg, 63%). 1H NMR: δ 5.37 (t, J ) 2.0 Hz, 2 H), 4.94 (t,
J ) 1.6 Hz, 2 H), 3.71 (s, 6 H), 3.02 (d, J ) 2.0 Hz, 2 H), 3.01
(d, J ) 1 6 Hz, 2 H). 13C{1H} NMR. δ 172.0, 144.7, 106.0, 57.9,
53.2, 41.5.
Diels-Ald er Ad d u ct of (Z)-3 a n d Na p h t h ylq u in on e
(49). 1H NMR: δ 8.00-8.05 (m, 1 H), 7.95-7.99 (m, 1 H), 7.69-
7.74 (m, 2 H), 3.70 (s, 3 H), 3.69 (s, 3 H), 3.31-3.36 (m, 2 H),
3.12-3.16 (m, 1 H), 2.94-2.98 (m, 1 H), 2.76-2.85 (m, 3 H),
2.25-2.30 (m, 1 H), 1.96-1.99 (m, 1 H), 0.94 (dd, J ) 7.6, 8.4
Hz, 9 H), 0.59-0.65 (m, 6 H). 13C {1H} NMR: δ 199.6, 197.1,
172.9, 172.5, 134.8, 134.6, 133.6, 133.2, 127.6, 125.9, 58.1, 53.1,
48.2, 47.9, 44.5, 43.4, 27.0, 22.1, 7.9, 4.2. IR (neat, cm-1): 2952,
2874, 2362, 2343, 1735, 1690, 1539, 1436, 1252, 1200, 1160,
1116, 1069. HRMS calcd (found) for C27H34O6Si: 482.2125
(482.2122).
Diels-Ald er Ad d u ct of (Z)-3 a n d N-P h en ylm a leim id e
(45a ). A solution of (Z)-3 (88 mg, 0.27 mmol) and N-phenyl-
maleimide (50 mg, 0.29 mmol) in toluene (4 mL) was stirred
at 80 °C for 20 h and concentrated under vacuum. Chroma-
tography of the residue (SiO2; hexanes-EtOAc ) 10:1 f 3:1)
Diels-Ald er Ad d u ct of (Z)-3 a n d Tetr a cya n oeth ylen e
1
(50). Yellow solid, mp 137-139 °C. H NMR: δ 3.74 (s, 3 H),
1
gave 45a (138 mg, 102%) as a viscous colorless oil. H NMR:
3.73 (s, 3 H), 2.92-3.16 (m, 6 H), 2.58-2.59 (m, 1 H), 1.06 (t,
J ) 8.0 Hz, 9 H), 0.92 (m, 3 H), 0.77-0.86 (m, 3 H). 13C{1H}
NMR: δ 171.5, 171.3, 131.6, 125.2, 112.7, 111.8, 111.4, 110.5,
57.9, 53.7, 53.6, 43.5, 43.3, 42.1, 40.4, 32.8, 32.1, 7.9, 3.8. IR
(neat, cm-1): 1735, 1654, 1437, 1268, 1203. HRMS calcd
(found) for C23H29N4O4Si (MH+): 453.1958 (453.1963).
Diels-Ald er Ad d u ct of (Z)-3 a n d 4-P h en yl-[1,2,4]tr ia -
zole-3,5-d ion e (51). A solution of 1 (100 mg, 0.48 mmol), 2a
(12 mg, 0.025 mmol), B(C6F5)3 (12 mg, 0.025 mmol), and HSiEt3
(150 µL, 0.93 mmol) in toluene (20 mL) was heated at 110 °C
for 2 h. The resulting solution of (Z)-3 was cooled to 0 °C,
treated with 4-phenyl-[1,2,4]triazole-3,5-dione (100 mg, 0.57
mmol), warmed to room temperature over 1 h, and concen-
trated under vacuum. Chromatography of the residue (SiO2;
hexanes-EtOAc ) 3:1) gave 51 (178 mg, 73%) as a white solid,
mp 45-47 °C. 1H NMR (300 MHz): δ 7.50-7.30 (m, 5 H), 4.39
(br s, 1 H), 4.24 (d, J ) 15.3 Hz, 1 H), 4.00 (d, J ) 14.7 Hz, 1
H), 3.22 (d, J ) 15.5 Hz, 1 H), 3.08 (br s, 2 H), 3.03 (d, J )
15.3, 1 H), 0.95 (t, J ) 7.8 Hz, 9 H), 0.66 (q, J ) 7.8 Hz, 3 H),
0.62 (q, J ) 7.8 Hz, 3 H). 13C{1H} NMR (75 MHz): δ 171.8,
171.6, 154.1, 149.2, 131.5, 131.0, 129.2, 128.1, 125.4, 123.3,
58.6, 53.3, 53.2, 46.2, 46.1, 42.3, 42.3, 41.0, 7.2, 2.9. Anal. Calcd
(found) for C25H33N3SiO6; H, 6.66 (6.79); C, 60.10 (59.74); N,
8.41 (8.22).
δ 7.39 (t, J ) 7.6 Hz, 2 H), 7.31 (t, J ) 10.8 Hz, 1 H), 7.19 (d,
J ) 7.6 Hz, 2 H), 3.68 (s, 3 H), 3.60 (s, 3 H), 3.28 (dt, J ) 1.6,
8.4 Hz, 1 H), 3.17 (dd, J ) 1.6, 8.4 Hz, 1 H), 3.02 (br d, J ) 14
Hz, 1 H), 2.97 (br d, J ) 12 Hz, 1 H), 2.93 (br d, J ) 12 Hz, 1
H), 2.89 (br d, J ) 12 Hz, 1 H), 2.85 (br d, J ) 15 Hz, 1 H),
2.59 (br d, J ) 15 Hz, 1 H), 2.54 (s, 1 H), 2.30-2.34 (m, 1 H),
0.97 (t, J ) 7.6 Hz, 9 H), 0.61 (q, J ) 7.6 Hz, 6 H). 13C{1H}
NMR: δ 180.0, 179.4, 172.6, 172.3, 134.3, 132.4, 129.2, 128.7,
127.8, 126.7, 58.2, 53.0, 44.8, 44.0, 40.8, 40.1, 25.0, 24.8, 7.6,
3.5. IR (neat, cm-1): 2953, 2911, 2876, 1737, 1730, 1712, 1598,
1257, 1197. HRMS calcd (found) for C27H35NO6Si (M+): 497.2234
(497.2220).
The procedure used to synthesize 45a was applied to the
synthesis of the remaining Diels-Alder adducts, except where
noted. Yields, reaction conditions, and isomer ratios are given
in Table 3. All Diels-Alder adducts were isolated as colorless
oils unless noted otherwise.
Diels-Ald er Ad d u ct of (E)-3 a n d N-P h en ylm a leim id e
(45b). 1H NMR: δ 7.41-7.45 (m, 2 H), 7.34-7.36 (m, 1 H),
7.19-7.21 (m, 2 H), 3.72 (s, 3 H), 3.65 (s, 3 H), 3.34 (dd, J )
6.0, 8.0 Hz, 1 H), 3.25 (dt, J ) 4.0, 8.6 Hz, 1 H), 2.99-3.09 (m,
4 H), 2.60 (br d, J ) 15.8 Hz, 1 H), 2.36 (br dd, J ) 8.4, 16.4
Hz, 1 H), 1.99 (m, 4 H), 0.97 (t, J ) 8.0 Hz, 9 H), 0.54-0.83
(m, 6 H). 13C{1H} NMR: δ 179.3, 178.3, 172.3, 135.3, 129.5,
128.9, 126.9, 58.7, 53.2, 44.3, 43.2, 41.5, 25.2, 23.6, 8.2, 4.8.
IR (neat, cm-1): 2951, 2362, 2433, 1734, 1709, 1498, 1381,
1262, 1195, 1168, 1070. HRMS calcd (found) for C27H35NO6Si
(M+): 497.2234 (497.2229).
Diels-Ald er Ad d u ct of (Z)-3 a n d Met h yl P r op iola t e
(52). A solution of methyl propiolate (200 µL, 2.2 mmol), Z-3
(49 mg, 0.15 mmol) and benzoquinone (e1 mg) was heated at
130 °C for 24 h and concentrated under vacuum. Chromatog-
raphy of the residue (SiO2; hexanes-EtOAc ) 35:1 f 4:1) gave
1
52 (31 mg, 51%). H NMR: δ 7.95 (d, J ) 1.2 Hz, 1 H), 7.82
(d, J ) 1.2 Hz, 1 H), 3.87 (s, 3 H), 3.72 (s, 6 H), 3.59 (s, 2 H),
(37) Trost, B. M.; Zhi, L.; Imi, K. Tetrahedron Lett. 1994, 35, 1361.
(38) Trost, B. M.; Lee, D. C. J . Am. Chem. Soc. 1988, 110, 7255.
3.57 (s, 2 H), 0.89-0.94 (m, 9 H), 0.83-0.87 (m, 6 H). 13C {1H}