ReactiVity of the Germene Mes2GedCR2
Organometallics, Vol. 26, No. 15, 2007 3733
solution in Et2O or toluene (when solid) via syringe. After the end
of the addition, the reaction mixture was slowly warmed to room
temperature and stirred overnight, to lead to a yellow solution
(except for other colors when indicated). A 1H and 13C NMR study
of the crude solution showed in all cases the complete reaction of
1 and the unique formation of one type of adduct. The solvents
were removed under reduced pressure, 30 mL of pentane was added,
and LiF was removed by filtration. The yields in the cycloadducts
were calculated from isolated crystals (after crystallization at -20
°C in pentane) from the starting Mes2Ge(F)CHR2.
(OCdCH), 171.34 (COOEt). MS (EI, 70 eV, m/z): 477 (Mes2-
GedCR2 + H, 2), 329 (Mes2GeO + H, 5), 313 (Mes2Ge + H,
10), 165 (CHR2, 100). IR: ν(CO), 1742.4 cm-1; ν(CdC), 1605.3
cm-1. Anal. Calcd for C39H42GeO4 (647.350): C, 72.36; H, 6.54.
Found: C, 71.82; H, 6.30.
Synthesis of 4 (1 and Diethyl Oxalate). Yield: 1.04 g (79%)
of white crystals of oxagermetane 4 (mp 180 °C). 1H NMR (250.13
3
MHz): δ 0.39 (t, JHH ) 7.2 Hz, 3H, OCH2CH3), 0.88 (broad s,
3
3H, o-Me of Mes), 1.21 (t, JHH ) 7.2 Hz, 3H, OCH2CH3), 2.19
(s, 3H, p-Me of Mes), 2.24 (broad s, 6H, o-Me of Mes), 2.31 (s,
3H, p-Me of Mes), 2.70 (broad s, 3H, o-Me of Mes), 3.25 and
4.17 (2 dq, 2JHH ) 7.2 Hz, 3JHH ) 7.2 Hz, 2 × 1H, CHH′CH3 and
CHH′CH3 for one Et group), 3.46 and 3.80 (2 dq, 2JHH ) 10.7 Hz,
3JHH ) 7.3 Hz, 2 × 1H, CHH′CH3 and CHH′CH3 for the other Et
group), 6.35-6.80 (very broad s, 2H, arom H of Mes), 6.83 (s,
2H, arom H of Mes), 7.05 (1H), 7.16 (1H), and 7.36 (2H) (3 t,
3JHH ) 7.6 Hz, H2,3,6,7 of CR2), 7.28, 7.43, 7.24, and 7.99 (4 d,
3JHH ) 7.6 Hz, 4 × 1H, H1,4,5,8 of CR2). 13C NMR (75.47 MHz):
δ 13.13 and 14.78 (OCH2CH3), 21.01 and 21.13 (p-Me of Mes),
22.84 (o-Me of Mes), 59.51 and 60.32 (OCH2CH3), 70.20 (CR2),
106.14 (OCO), 119.24 and 119.31 (C4,5), 124.05, 126.52, 126.56,
126.67, 126.81, and 128.20 (C1-3, C6-8 of CR2), 128.60 (broad
s) and 129.18 (m-C of Mes), 131.33 and 131.72 (ipso-C of Mes),
139.85, 139.89, 140.01, 140.22, 141.15, 143.19, and 144.13 (C10-
13, o- and p-C of Mes), 168.14 (CO). MS (EI, 70 eV, m/z): 622
(M, 3), 577 (M - OEt, 5), 476 (Mes2GedCR2, 10), 357 (MesGed
CR2, 20), 311 (Mes2Ge - H, 60), 220 (R2CCOEt - H, 25), 165
(CHR2, 100). IR: ν(CO), 1725.4 cm-1. Anal. Calcd for C37H40-
GeO4 (621.312): C, 71.53; H, 6.49. Found: C, 71.52; H, 6.20.
Synthesis of 2 (1 and Methyl Acrylate). Yield: 1.01 g (85%)
of white crystals of oxagermacyclohexene 2 (mp 220 °C). 1H NMR
(300.13 MHz): δ 1.30-3.20 (extremely broad m, 20H, Me of Mes
3
and CH2), 3.71 (s, 3H, OMe), 3.89 (t, JHH ) 5.2 Hz, 1H, CHd),
6.73 (very broad s (half-width 40 Hz), 4H, arom H of Mes), 7.12-
3
7.44 (m, 6H, arom H of CR2), 7.81 (d, JHH ) 7.9 Hz, 2H, H on
C1,8 or C4,5 of CR2). 13C NMR (75.47 MHz): δ 20.99 (p-Me of
Mes), 22.72 (o-Me of Mes), 34.31 (CH2), 48.42 (CR2), 54.60
(OMe), 68.72 (CHd), 119.72 (C4,5), 125.03, 126.67, 126.92,
129.28 (C1-3, C6-8, m-CH of Mes), 134.41, 139.38, 140.47,
148.38 (ipso-, o-, and p-C of Mes and C10-13), 160.23 (OCd).
MS (EI, 70 eV, m/z): 562 (M, 3), 476 (Mes2GedCR2, 65), 311
(Mes2Ge - H, 100). Anal. Calcd for C35H36GeO2 (561.260): C,
74.90; H, 6.47. Found: C, 75.05; H, 6.60.
Synthesis of 3a (1 and (Z)- and (E)-MeOOCCHdCHCOOMe).
(a) Dimethyl maleate: yield 0.87 g (70%) of white crystals of
oxagermacyclohexane 3a (mp 209 °C). (b) Dimethyl fumarate:
yield 0.97 g (78%). 1H NMR (300.13 MHz): δ 0.70 (broad s, 3H,
o-Me of Mes), 1.40 (very broad s (half-width 45 Hz), 3H, o-Me of
Mes), 2.04 and 2.27 (2 s, 2 × 3H, p-Me of Mes), 2.34 (broad s,
3H, o-Me of Mes), 2.70 (very broad s (half-width 40 Hz), 3H, o-Me
of Mes), 2.83 and 3.67 (2 s, 2 × 3H, OMe), 3.84 and 4.34 (2 d,
3JHH ) 2.4 Hz, 2 × 1H, OCdCHCHCOOMe), 6.38 and 6.65 (2
broad s, 2 × 2H, arom H of Mes), 6.73, 7.55, 7.71, and 7.73 (4 d,
3JHH ) 7.6 Hz, 4 × 1H, H1,4,5,8 of CR2), 7.01, 7.20, 7.26, and
Synthesis of 5 (1 and Maleic Anhydride). The carbonyl
compound was dissolved in Et2O, and the reaction mixture turned
green and then turquoise blue. Yield: 0.87 g (75%) of white crystals
1
of oxagermetane 5 (mp 243 °C). H NMR (250.13 MHz): δ 0.91
(broad s, 3H, o-Me of Mes), 2.20 (extremely broad s (half-width
120 Hz), 6H, o-Me of Mes), 2.23 and 2.32 (2 s, 2 × 3H, p-Me of
3
7.33 (4 t, JHH ) 7.6 Hz, 4 × 1H, H2,3,6,7 of CR2). 13C NMR
3
Mes), 2.61 (broad s, 3H, o-Me of Mes), 5.77 (d, JHH ) 5.5 Hz,
(75.47 MHz): δ 20.79 and 21.08 (p-Me of Mes), 22.74 (o-Me of
Mes), 48.69, 51.08, and 54.77 (CHCR2 and 2 OCH3), 50.31 (CR2),
69.16 (OCdCH), 119.36 and 119.53 (C4,5), 125.07, 125.87, 126.11,
126.29, 126.87, 127.02, 127.14, and 129.70 (C1-3, C6-8, and
m-C of Mes), 133.30 and 134.24 (ipso-C of Mes), 139.27, 139.98,
141.13, 141.80, 143.85, and 145.60 (C10-13, o- and p-C of Mes),
160.16 (OCdCH), 171.72 (COOEt). MS (EI, 70 eV, m/z): 620
(M, 2), 606 (M - Me + H, 1), 589 (M - OMe, 2), 561 (M -
COOMe, 1), 476 (Mes2GedCR2, 100), 311 (Mes2Ge - H, 90),
165 (CHR2, 30). Anal. Calcd for C37H38GeO4 (619.296): C, 71.76;
H, 6.18. Found: C, 71.92; H, 6.20.
1H, dCHCdO), 6.58 (broad s, 1H, arom H of Mes), 6.87 (broad
3
s, 3H, arom H of Mes), 7.17 (d, JHH ) 5.5 Hz, 1H, OCCHd),
7.16, 7.23, 7.34, and 7.39 (4 t, 3JHH ) 7.6 Hz, 4 × 1H, H2,3,6,7 of
3
CR2), 7.46, 7.66, 7.77, and 7.80 (4 d, JHH ) 7.6 Hz, 4 × 1H,
H1,4,5,8 of CR2). 13C NMR (75.47 MHz): δ 21.04, 21.09, 22.16,
22.61, and 22.93 (o- and p-Me of Mes), 70.95 (CR2), 116.12 (CO2),
119.46 and 120.16 (C4,5 of CR2), 122.90, 124.26, 127.12, 127.49,
and 127.70 (C1-3, C6-8 of CR2, OdCCHd), 128.55 and 129.05
(2 broad s, m-CH of Mes), 130.53 and 131.20 (ipso-C of Mes),
139.10, 139.68, 140.31, 140.43, 140.62, 142.25, 143.04, and 143.60
(C10-13 of CR2, o- and p-C of Mes), 152.14 (O-CCHd), 169.35
(CdO). MS (EI, 70 eV, m/z): 574 (M, 5), 476 (Mes2GedCR2,
10), 411 (M - Mes - CO2, 7), 311 (Mes2Ge - H, 20), 246 (M -
Mes2GeO, 45), 218 (M - Mes2GeO - CO, 50), 193 (MesGe, 50),
189 (M - Mes2Ge - CO2 - CO - H, 100), 165 (CHR2, 60), 44
(CO2, 65). IR: ν(CO), 1695.0 cm-1. Anal. Calcd for C35H32GeO3
(573.227): C, 73.34; H, 5.63. Found: C, 73.52; H, 5.86.
Synthesis of 3b (1 and Diethyl Fumarate, (Z)-EtOOCCHd
CHCOOEt). Yield: 0.97 g (71%) of white crystals of 3b (mp 170
3
°C). 1H NMR (300.13 MHz): δ 0.40 (t, JHH ) 7.2 Hz, 3H,
OCH2CH3), 0.68 and 1.18 (2 broad s, 2 × 3H, o-Me of Mes), 1.26
3
(t, JHH ) 7.2 Hz, 3H, OCH2CH3), 2.01 and 2.24 (2 s, 2 × 3H,
p-Me of Mes), 2.31 (broad s, 3H, o-Me of Mes), 2.72 very broad
2
3
s, o-Me of Mes), 3.28 (AB q, JHH ) 9.0 Hz, JHH ) 7.2 Hz, 1H,
2
3
Synthesis of 6 (1 and 4-Cyclopentene-1,3-dione, 1:1 Molar
Ratio). The carbonyl compound was dissolved in toluene. Yield:
0.92 g (80%) of white crystals of oxagermetane 6 (mp 205 °C). 1H
NMR (300.13 MHz): δ 0.94 and 1.48 (2 broad s, 2 × 3H, o-Me
of Mes), 2.14 (d, 2JHH ) 18.6 Hz, 1H, CHH′), 2.16 and 2.27 (2 s,
2 × 3H, p-Me of Mes), 2.58 (broad s, 3H, o-Me of Mes), 2.60 (d,
2JHH ) 18.6 Hz, 1H, CHH′), 2.85 (broad s, 3H, o-Me of Mes),
5.89 (d, 3JHH ) 6.0 Hz, 1H, OdCCHd), 5.90, 6.51, 6.65, and 6.81
(4 broad s, 4 × 1H, arom H of Mes), 7.00-7.13 (m, 2H, arom H
of CR2), 7.25-7.32 (m, 3H, arom H of CR2), 7.54, 7.71, and 7.74
OCHAHBCH3), 3.29 (AB q, JHH ) 9.0 Hz, JHH ) 7.2 Hz, 1H,
3
OCHAHBCH3), 3.89 and 4.31 (2 d, JHH ) 2.4 Hz, 2 × 1H, OCd
CHCHCOOEt), 3.92 (q, 3JHH ) 7.2 Hz, 2H, OCH2CH3), 6.33 and
6.60 (2 broad s, 2 × 2H, arom H of Mes), 6.73, 7.59, 7.68, and
3
7.69 (4 d, JHH ) 7.6 Hz, 4 × 1H, H1,4,5,8 of CR2), 6.97, 7.16,
7.23, and 7.30 (4 t, 3JHH ) 7.6 Hz, 4 × 1H, H2,3,6,7 of CR2). 13
C
NMR (75.47 MHz): δ 13.31 and 14.96 (OCH2CH3), 21.08 and
21.11 (p-Me of Mes), 22.74 and 22.88 (o-Me of Mes), 48.73
(CHCR2), 50.44 (CR2), 59.90 and 62.84 (OCH2CH3), 70.61 (OCd
CH), 119.31 and 119.48 (C4,5), 125.29, 126.26, 126.31, 126.81,
127.04, and 127.15 (C1-3, C6-8), 128.55 and 129.71 (m-C of
Mes), 133.54 and 134.57 (ipso-C of Mes), 139.23, 139.92, 141.26,
142.56, 144.03, and 145.86 (C10-13, o- and p-C of Mes), 159.05
3
(3 d, JHH ) 7.8 Hz, 3 × 1H, H on C1, C4, C5, or C8), 8.15 (d,
3JHH ) 6.0 Hz, 1H, OCCHd). 13C NMR (75.47 MHz): δ 21.00
and 21.08 (p-Me of Mes), 22.38, 22.71, and 23.32 (o-Me of Mes),