R. Laı¨ et al. / Journal of Organometallic Chemistry 693 (2008) 23–32
29
5.3. Cyclopentadiene ethyl lactate 2
fication on a silica gel column, 1.9 g of 7 (45% yield), 0.34 g
of 8 (8% yield) and 0.06 g of 9 (2% yield). The Rf of 8 and 9
are 0.47 and 0.40, respectively (hexane/Et2O 80/2). The
optical purity found for 7 was 95% by chiral HPLC. The
same value was found from 8 after protonation and
reprotonation.
1H NMR (CDCl3, 200 MHz): d 6.54, 6.43, 6.33, 6.17 (m,
3H, CH Cp), 4.15 (q, 2H, CH2CH3), 4.13 (q, 2H,
CH2CH3), 3.58 (q, 1H, CHCH3), 3.55 (q, 1H, CHCH3),
2.98 (m, 4H, CH2 Cp), 1.40 (d, 3H, CHCH3), 1.25 (t, 3H,
CH2CH3). 13C NMR (CDCl3, 50 MHz): d 173.7 (C@O),
146.0 (Cquat Cp), 145.5 (Cquat Cp), 134.0, 133.2, 132.1,
128.2, 127.5, 126.1 (CH Cp), 60.6 (CH2CH3), 42.0 (CH2
Cp), 41.4 (CHCH3), 41.3 (CH2 Cp), 40.6 (CHCH3), 17.5
(CHCH3), 16.7 (CHCH3), 14.5 (CH2CH3), 14.3 (CH2CH3).
Anal. Calc. for C10H14O2: C, 72.23; H, 8.42. Found: C,
72.45; H, 8.36%.
5.7. Indene ethyl lactate ((S)-ethyl 2-(1H -inden-3-yl)
propanoate) 7
1H NMR (CDCl3, 200 MHz): d 7.47–7.22 (m, 4H, CH
arom), 6.40 (m, 1H, CH indene), 4.16 (q, 7.2, 2H,
CH2CH3), 3.81 (qdd, 7.1, 1.5, 0.9, 1H, CHCH3), 3.37 (bs,
2H, CH2 indene), 1.55 (d, 7.1, 3H, CHCH3), 1.23 (t, 7.2,
3H, CH2CH3). 13C NMR (CDCl3, 50 MHz): d 174.3
(C@O), 144.4 (Cquat arom), 144.0 (Cquat arom), 143.2
(Cquat indene), 129.4 (CH indene), 126.1, 124.8, 123.9,
119.5 (CH arom), 60.9 (CH2CH3), 39.1 (CHCH3), 37.9
(CH2 indene), 16.6 (CHCH3), 14.1 (CH2CH3). Anal. Calc.
for C14H16O2: C, 77.74; H, 7.45. Found: C, 77.03; H,
5.4. Disubstituted cyclopentadiene ethyl lactate (diethyl
(2S,20S)-2,20-cyclopenta-1,3-diene-1,3-
diyldipropanoate and diethyl (2S,20S)-2,20-cyclopenta-1,3-
diene-1,4-diyldipropanoate) 3
1H NMR (CDCl3, 200 MHz): d 6.54–6.04 (m, 2H, CH
C5H4), 4.13 (m, 4H, CH2CH3), 3.77 (q, 1H, CHCH3),
3.46 (q, 1H, CHCH3), 2.99 (m, 4H, CH2 Cp), 1.37 (m,
6H, CHCH3), 1.23 (6H, m, CH2CH3). 13C NMR (CDCl3,
50 MHz): d 173.0 (C@O), 147.0 (Cquat Cp), 146.0 (Cquat
Cp), 134.0, 133.5, 132.3, 132.0 (CH Cp), 60.3 (CH2CH3),
42.1 (CH2 Cp), 41.5 (CHCH3), 41.3 (CH2 Cp), 40.6
(CHCH3), 17.6 (CHCH3), 16.9 (CHCH3), 14.5 (CH2CH3),
14.1 (CH2CH3). Anal. Calc. for C15H22O4: C, 67.76; H,
8.31. Found: C, 68.20; H, 8.56%.
25
7.64%. For the (S)-enantiomer, ½aꢂD ¼ þ25:6 (CHCl3,
c = 6.75).
5.8. Indene ethyl lactate ((S)-ethyl 2-(1H-inden-1-yl)
propanoate) 8
Only the NMR data of the major diastereoisomer will be
given.
1H NMR (CDCl3, 200 MHz): d 7.30 (m,4 H, CH arom),
6.86 (dd, 1 H, CH-sp2indene), 6.49 (dd, 1 H, CH-sp2in-
dene), 4.25 (q, 2 H, CH2–O), 3.88 (m, 1 H, CH-sp3 indene),
2.99 (q, 1 H, CH–CH3), 1.32 (t, 3 H, CH3–CH2), 0.84 (d, 3
H, CH3–CH). 13C NMR (CDCl3, 50 MHz): d 175.7
(C@O), 145.4 and 144.8 (Cquat arom), 136.2 and 132.7
(CH-sp2 indene), 127.0, 125.0, 122.7 and 121.2 (CH arom),
60.7 (CH2–O), 52.0 (CH-sp3 indene), 40.9 (CH–CH3), 12.4
(CH3–CH), 12.2 (CH3–CH2).
5.5. Synthesis of indene lactate ((S)-ethyl 2-(1H -inden-3-
yl)propanoate) 7 from tosylate of ethyl (S)-(ꢀ) lactate 1
A solution of LiInd (4.4 g, 36 mmol), prepared from
Indene and BuLi (2.5 M in hexane) in hexane, in 100 ml
THF was slowly added over 2 h to a solution of 10 g
(360 mmol) of tosylate of ethyl lactate 1 in THF (200 ml)
cooled at ꢀ78 ꢁC. The solution was stirred overnight at
room temperature. After evaporation of THF under vac-
uum, addition of a saturated aqueous solution of NaCl
extraction of the organic compounds was made with
Et2O (5 · 50 ml). The combined extracts were dried over
MgSO4 and Et2O was eliminated under vacuum leaving
the crude product as an oily brown residue. Purification
on a silica gel column afforded 4.5 g of 7 (56.5% yield).
The Rf of 7 is 0.43 (hexane/Et2O 80/2).
5.9. Disubstituted indene ethyl lactate (diethyl (2S,20S)-
2,20-(1H-indene-1,3-diyl)dipropanoate) 9
1H NMR (CDCl3, 400 MHz): d 7.35 (ddc, 7.4, 1H, CH
arom), 7.33 (ddc, 7.8, CH arom), 7.26 (tc, 7.4, 1H, CH
arom), 7.18 (ddd, 7.3, 1.1, 1H, CH arom), 6.31 (dd, 1.95,
1.2, 1H, CH indene), 4.24 (q, 7.1, 2H, CH2-9), 4.13 (qd,
7.1, 1.1, 2H, CH2-7), 3.86 (mc, 1H, CH-3), 3.76 (qt, 7.0,
1.2, 1H, CH-4), 2.98 (qd, 7.0, 5.0, 1H, CH-2), 1.52 (d,
7.1, 3H, CH3-6), 1.31 (t, 7.1, 3H, CH3-10), 1.18 (t, 7.1,
3H, CH3-8), 0.78 (d, 7.0, 3H, CH3-1). 13C NMR (CDCl3,
100 MHz): d 175.7 (C-19), 174.0 (C-18), 146.1 (C-11),
144.1 (C-16), 144.1 (C-17), 131.4 (C-5), 126.9 (C-14),
125.3 (C-13), 122.8 (C-12), 119.6 (C-15), 60.8 (C-7), 60.7
(C-9), 50.5 (C-3), 41.4 (C-2), 39.1 (C-4), 16.5 (C-6), 14.4
(C-10), 14.2 (C-8), 11.7 (C-1). Anal. Calc. for C19H24O4:
C, 72.12; H, 7.63. Found: C, 72.36; H, 7.45%.
Chiral HPLC: Chiralcel OJ (250 · 4.6 mm), hexane/iso-
propanol (90/10) as mobile phase, flow-rate = 1 ml/mn,
25 ꢁC, detection by UV at 254 nm and polarimeter, Rt(S,
+) = 7.48, Rt(R,ꢀ) = 11.90, k(S) = 1.45, k(R) = 2.90,
a = 2.00 and Rs = 6.17.
5.6. Synthesis of indene lactate ((S)-ethyl 2-(1H -inden-3-
yl)propanoate) 7 from triflate of ethyl lactate 6
In the same conditions as those described above, 4.9 g
(19.6 mmol) of triflate of ethyl lactate 6 afforded, after puri-
25
½aꢂ546 ¼ ꢀ58:6 (CH2Cl2, c = 0.365).