Synlett 2006(20): 3395-3398  
DOI: 10.1055/s-2006-956453
LETTER
© Georg Thieme Verlag Stuttgart · New York

Asymmetric Synthesis of (+)-CP-99,994 and (+)-L-733,060 from Enantio­merically Pure (3S,4S)-4-(tert-Butylcarbamoyl)-4-phenyl-1-buten-3-ol

Tetsuta Oshitari, Tadakatsu Mandai*
Department of Life Science, Kurashiki University of Science & the Arts, 2640 Nishinoura, Tsurajima, Kurashiki 7128505, Japan
Fax: +81(86)4401062; e-Mail: ted@chem.kusa.ac.jp;
Further Information

Publication History

Received 19 September 2006
Publication Date:
08 December 2006 (online)

Abstract

Asymmetric syntheses of neurokinin substance P receptor antagonists (+)-CP-99,994 and (+)-L-733,060 have been accomplished starting from enantiomerically pure (3S,4S)-4-(tert-butylcarbamoyl)-4-phenyl-1-buten-3-ol.

9

In our preliminary investigation, DMSO was proven to be more effective solvent than toluene, THF and DMF. In addition, we found that DBU, soluble in above solvents, was much superior to other bases such as NaH, t-BuOK and Cs2CO3.

11

The reaction under heating at refluxing temperature in a flask overnight provided 4-phenyl-4-(3-aminopropion-amido)-3-tosylamino-1-butene as the sole product.

12

After removal of ethylenediamine in vacuo, a mixture of the mono-N-Ts-protected 1,2-diamine and 2-imidazolidone was afforded, which was subjected to the next step without further purification.

15

Five-membered N-Boc-enamide (2%) and five-membered N-Boc-aminals (5%) were also isolated after the treatment with CSA. N-Ts-enamide and N-Ts-aminals were not obtained at all.

16

Compound 10: colorless foam; [α]D 22 -206.0 (c = 1.00, CHCl3). 1H NMR (CDCl3): δ = 1.21 (br s, 6.3 H), 1.41 (br s, 2.7 H), 1.77-1.85 (m, 1 H), 1.89-2.10 (br m, 1 H), 2.45 (s, 3 H), 3.87 (m, 1 H), 3.97 (d, J = 10.1 Hz, 1 H), 4.71 (br, 0.3 H), 4.78 (br, 0.7 H), 4.98 (br, 0.7 H), 5.15 (br, 0.3 H), 6.89-7.22 (m, 2 H), 7.28-7.38 (m, 5 H), 7.78 (m, 2 H). 13C NMR (CDCl3): δ = 21.6, 25.5, 26.1, 27.9, 28.2, 49.8, 57.5, 58.9, 77.2, 81.3, 81.5, 101.0, 126.2, 126.6, 127.0, 128.0, 128.5, 129.9, 137.3, 137.7, 138.1, 143.7, 152.1. Anal. Calcd for C23H28N2O4S: C, 64.46; H, 6.59; N, 6.54. Found: C, 64.37; H, 6.71; N, 6.54.

17

In the absence of TBAI, the N-alkylation was very slow at 0 °C. Compound 12, however, was afforded in 81% yield at r.t. in 5 h with the significant loss of enantiomeric purity (77% ee), which was probably caused by the elimination-addition sequence of the N-2-methoxybenzyl-tert-butyl carbamoyl group.

18

Compound 12: colorless foam; [α]D 21 -105.2 (c = 1.32, CHCl3). 1H NMR (CDCl3): δ = 1.19-1.70 (m, 21 H), 1.85 (br m, 1 H), 3.14 (br m, 1 H), 3.33 (br m, 1 H), 3.65 (s, 3 H), 3.75 (br m, 0.45 H), 3.99-4.10 (m, 1.65 H), 4.25 (br m, 0.45 H), 4.50 (br m, 0.45 H), 5.45 (br s, 0.9 H), 5.64 (br s, 0.1 H), 6.71 (m, 1 H), 6.86 (m, 1 H), 7.03 (m, 1 H), 7.12 (m, 1 H), 7.37-7.25 (m, 5 H). 13C NMR (CDCl3): δ = 22.4, 24.6, 28.2, 41.0, 41.6, 42.1, 55.1, 56.2, 57.0, 57.5, 77.2, 79.6, 109.8, 120.2, 126.4, 127.0, 128.0, 128.4, 140.2, 141.2, 155.9. Anal. Calcd for C29H40N2O5: C, 70.13; H, 8.12; N, 5.64. Found: C, 69.90; H, 8.28; N, 5.54. The enantiomeric purity of 12 was determined to be >99% ee by HPLC [CHIRALCEL OD; hexane-i-PrOH = 30:1; λ = 220 nm; flow rate: 1.0 mL/min; t R(12) = 6.8 min; t R(ent-12) = 11.0 min].

19

(+)-CP-99,994 (1): 1H NMR (free base, CDCl3): δ = 1.40 (br d, J = 13.2 Hz, 1 H), 1.60 (m, 1 H), 1.76 (br s, 2 H), 1.93 (m, 1 H), 2.14 (br d, J = 13.1 Hz, 1 H), 2.76-2.83 (m, 2 H), 3.27 (m, 1 H), 3.41 (d, J = 13.8 Hz, 1 H), 3.44 (s, 3 H), 3.67 (d, J = 13.8 Hz, 1 H), 3.88 (d, J = 2.1 Hz, 1 H), 6.68 (br d, J = 8.2 Hz, 1 H), 6.80 (br t, J = 7.3 Hz, 1 H), 6.97 (dd, J = 1.5, 7.3 Hz, 1 H), 7.15 (dt, J = 1.5, 8.2 Hz, 1 H), 7.20-7.31 (m, 5 H). 13C NMR (free base, CDCl3): δ = 20.4, 28.2, 46.7, 47.8, 54.7, 54.8, 64.0, 109.8, 120.0, 126.3, 126.5, 127.8, 128.2, 129.6, 142.4, 157.6.

20

Protection of C3-hydroxyl group as a benzoate was of choice for the subsequent hydroformylation.

21

Compound 13: colorless viscous oil; [α]D 24 -152.3 (c = 1.02, CHCl3). 1H NMR (CDCl3): δ = 1.25 (br s, 6 H), 1.40-1.55 (br m, 3 H), 2.05-2.25 (m, 1 H), 2.40 (m, 1 H), 4.83 (br m, 0.33 H), 4.93 (br m, 0.67 H), 5.40 (br m, 0.33 H), 5.46-5.63 (m, 1.67 H), 7.00-7.35 (m, 6 H), 7.40 (m, 2 H), 7.55 (m, 1 H), 7.90 (m, 2 H). 13C NMR (CDCl3): δ = 23.7, 24.0, 27.9, 28.2, 56.0, 57.3, 69.2, 81.3, 100.4, 126.1, 126.4, 127.5, 127.6, 128.0, 128.35, 128.38, 129.69, 129.71, 129.8, 133.1, 138.6, 152.3, 165.6. Anal. Calcd for C23H25NO4: C, 72.80; H, 6.64; N, 3.69. Found: C, 72.76; H, 6.84; N, 3.66.

22

Five-membered aminals (4%) were also isolated.

23

Compound 14: colorless viscous oil; [α]D 22 +56.7 (c = 1.3, CHCl3) {Lit. [1g] [α]D 15 +53.77 (c = 1.0, CHCl3); Lit. [2d] [α]D 25 +38.30 (c = 1.92, CHCl3)}. 1H NMR (CDCl3): δ = 1.37 (s, 9 H), 1.54-1.62 (m, 1 H), 1.69 (m, 1 H), 1.76-1.87 (m, 3 H), 3.04 (m, 1 H), 4.01 (dd, J = 5.8, 12.8 Hz, 1 H), 4.09 (m, 1 H), 5.32 (d, J = 5.8 Hz, 1 H), 7.27 (m, 1 H), 7.37-7.32 (m, 2 H), 7.45 (m, 2 H). 13C NMR (CDCl3): δ = 23.1, 27.7, 28.3, 39.5, 59.3, 70.1, 79.9, 127.2, 128.4, 138.5, 155.4. Anal. Calcd for C16H23NO3: C, 69.29; H, 8.36; N, 5.05. Found: C, 69.21; H, 8.59; N, 4.77. The enantiomeric purity of 14 was determined to be >99% ee by HPLC [CHIRALCEL OJ-H; hexane-i-PrOH = 9:1; λ = 220 nm; flow rate: 1.0 mL/min; t R(14) = 4.80 min; t R(ent-14) = 5.75 min].

24

Compound 15: colorless oil; [α]D 23 +43.3 (c = 1.60, CHCl3) {Lit. [1g] [α]D 28 +36.90 (c = 1.0, CHCl3)}. 1H NMR (CDCl3): δ = 1.46 (s, 9 H), 1.58-1.76 (m, 2 H), 1.94-2.05 (m, 2 H), 2.77 (ddd, J = 3.3, 13.4, 13.4 Hz, 1 H), 3.88 (m, 1 H), 3.95 (dd, J = 3.3, 13.4 Hz, 1 H), 4.71 (d, J = 12.5 Hz, 1 H), 4.75 (d, J = 12.5 Hz, 1 H), 5.70 (br s, 1 H), 7.25-7.36 (m, 3 H), 7.54 (br s, 1 H), 7.56 (br s, 1 H), 7.71 (br s, 2 H), 7.78 (br s, 1 H). 13C NMR (CDCl3): δ = 24.2, 25.8, 28.4, 39.2, 55.4, 69.1, 78.7, 80.1, 121.4 (m), 123.3 (q, J = 272 Hz), 127.0, 127.2, 128.28, 128.32, 131.6 (q, J = 32.9 Hz), 138.0, 141.0, 155.3. The enantiomeric purity of 15 was determined to be >99% ee by HPLC [CHIRALPAK IA; hexane-i-PrOH = 30:1; λ = 220 nm; flow rate: 0.3 mL/min; t R(15)= 14.1 min; t R(ent- 15) = 16.6 min)].

25

L-733,060 (2): 1H NMR (free base, CDCl3): δ = 1.53 (m, 1 H), 1.66-1.75 (m, 1 H), 1.88 (m, 1 H), 2.22 (br d, J = 14.0 Hz, 1 H), 2.85 (ddd, J = 3.1, 12.5, 12.5 Hz, 1 H), 3.29 (m, 1 H), 3.68 (br m, 1 H), 3.85 (d, J = 1.2 Hz, 1 H), 4.13 (d, J = 12.5 Hz, 1 H), 4.52 (d, J = 12.5 Hz, 1 H), 7.25-7.29 (m, 1 H), 7.30-7.35 (m, 2 H), 7.35-7.39 (m, 2 H), 7.44 (br s, 2 H), 7.69 (br s, 1 H). 13C NMR (free base, CDCl3): δ = 20.5, 28.4, 47.1, 64.2, 70.0, 77.3, 121.1 (hept, J = 4.1 Hz), 123.2 (q, J = 271 Hz), 126.7, 127.0, 127.4 (m), 128.1, 131.2 (q, J = 32.9 Hz), 141.2, 141.9.