Enantioselective reactions of α-methoxybenzyllithium generated by t-BuLi/chiral bis(oxazoline) complex with aldehydes

Tetrahedron Letters

Volumn 40, Issue 37, 1999, Pages 6813-6816

  Tomooka, Katsuhiko ^a   Wang, Lan Fang ^a   Komine, Nobuyuki ^a   Nakai, Takeshi ^a  

^a TOKYO INSTITUTE OF TECHNOLOGY   (Japan)

Author keywords

1,2 diol; Enantioselection; methoxybenzyllithium

Indexed keywords

ALDEHYDE; GLYCOL; LITHIUM DERIVATIVE; ORGANOLITHIUM COMPOUND; OXAZOLINE DERIVATIVE;

ARTICLE; CHEMICAL REACTION; DIASTEREOISOMER; ENANTIOMER; REACTION ANALYSIS; THERMODYNAMICS;

EID: 0033543757     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)01365-9     Document Type: Article

References (12)

1. Reviews on recent progress: (a) Beak, P.; Basu, A.; Gallageher, D. J.; Park, Y. S.; Thayumanavan, S. Acc. Chem. Res. 1996, 29, 552-560.
2. (b) Hoppe, D.; Hense, T. Angew. Chem., Int. Ed. Engl. 1997, 36, 2283-2316.
3. For our previous works in this area: Tomooka, K.; Komine, N.; Nakai, T. Tetrahedron Lett. 1998, 39, 5513-5516; Tomooka, K.; Komine, N.; Sasaki, T.; Shimizu, H.; Nakai, T. Tetrahedron Lett. 1998, 39, 9715-9718.
4. For our previous works in this area: Tomooka, K.; Komine, N.; Nakai, T. Tetrahedron Lett. 1998, 39, 5513-5516; Tomooka, K.; Komine, N.; Sasaki, T.; Shimizu, H.; Nakai, T. Tetrahedron Lett. 1998, 39, 9715-9718.
5. Tomooka, K.; Wang, L.-F.; Komine, N.; Nakai, T. Tetrahedron Lett. 1999, 40, 6809.
6. 11), 4.16 (d, J=6.3 Hz, 1H), 3.58 (m, 1H), and 3.22 (s, 3H); syn-4c, 4.11 (d, J=7.5 Hz, 1H), 3.47 (m, 1H), 3.22 (s, 3H); anti-4e (R=Ph-C≡C), 4.73 (m, 1H), 4.45 (d, J=4.2 Hz, 1H), 3.38 (s, 3H); syn-4e, 4.67 (d, J=7.5 Hz, 1H), 4.31 (d, 1H), 3.34 (s, 3H); anti-4f (TBDPS-C≡C), 4.69 (m, 1H), 4.47 (d, J=9.9 Hz, 1H), 3.41 (s, 3H); syn-4f, 4.63 (d, J=7.8 Hz, 1H), 4.47 (d, 1H), 3.29 (s, 3H).
7. The reaction of (S)-5 with the organolithium reagent gave an epimeric mixture of (1S)-4: anti:syn=57:43 for 4a (R=Ph), 77:33 for 4e (R=Ph-C≡C), and 79:21 for 4f (R=TBDPS-C≡C).
8. The four stereoisomers of the MTPA esters were distinguishable by four sets of doublets due to the two methines: for 4a (R=Ph), e.g., δ 6.48/4.40 (1R,2S), 6.31/4.34 (1S,2R), 6.43/4.28 (1R,2R), and 6.50/4.23 (1S,2S).
9. 3) of meso-1,2-dimethoxy-1,2-diphenylethane: δ 7.32-7.24 (m, 6H), 7.21-7.14 (m, 4H), 4.31 (s, 2H), 3.16 (s, 6H).
10. 3): benzaldehyde adduct, δ 7.64-6.85 (m, 9H), 4.85 (d, J=5.6 Hz, 1H), 4.28 (d, 1H), 3.78 (s, 3H), 3.19 (s, 3H) for the anti isomer; δ 7.64-6.85 (m, 9H), 4.63 (d, J=8.6 Hz, 1H), 4.06 (d, 1H), 3.75 (s, 3H), 3.27 (s, 3H) for the syn isomer; phenylpropynal adduct, δ 7.45-6.86 (m, 9H), 4.62 (m, 1H), 4.33 (d, J=4.2 Hz, 1H), 3.75 (s, 3H), 3.29 (s, 3H), 2.53 (br. s, 1H) for the anti isomer; δ 7.45-6.86 (m, 9H), 4.54 (d, J=7.7 Hz, 1H), 4.18 (d, 1H), 3.75 (s, 3H), 3.25 (s, 3H), 2.95 (br. s, 1H).
11. The definition and its general schematic energy profile, see Ref. 1a.
12. The propynal adduct 4e concurrently obtained in this experiment was of 94% ee (anti) and 57% ee (syn), which are significantly lower than those observed in the reaction with the propynal only (entry 6, Table 1).