( ± ) [134532-03-9],(R)-( + ) [137848-28-3],(S)-(-) [137848-29-4]  · C20H15NO  · (MW 285.34)

(chiral ligand1,2 and catalyst3)

Alternate Name: 2-amino-2-hydroxy-1,1-binaphthyl, NOBIN.

Physical Data: (±) mp 239-241 °C (benzene). (S)-(-) 171-173 °C (benzene), [a]D -117 (c 1.0, THF)1b or -120 (c 1.5, THF).1e

Solubility: (±) soluble very well in THF; well-soluble in CH2Cl2, AcOEt; less soluble in toluene and benzene; sparingly soluble in MeOH, EtOH; insoluble in hexane. (R)-( + ) and (S)-(-) are soluble very well in THF; well in CH2Cl2, AcOEt, toluene, and benzene; sparingly soluble in MeOH, EtOH, and hexane. Enantiopure NOBIN is much better soluble in heptane than the racemate, which can be used for obtaining a pure enantiomer from an enantiomerically enriched sample.4

Preparative Methods: racemic 2-amino-[1,1-binaphthalen]-2-ol (NOBIN) is most conveniently prepared in one step by the oxidative cross-coupling of a 1:1 mixture of 2-amino-naphtha-lene with 2-naphthol. The original method, employing the Cu(II)-mediated coupling in solution (1),1a has been later improved in form of a Fe(III)-mediated coupling in a quasi-solid-state.5 When the Cu(II)-coupling is carried out in the presence of a chiral amine, such as a-methylbenzylamine, the resulting NOBIN is obtained in up to 46% ee;1b,1c the latter product can be purified by crystallization to ~100% ee.1b Resolution of the racemate can be attained by crystallization with (1S)-( + )-10-camphorsulfonic acid from a 10:1 mixture of chlorobenzene and ethanol,1e which gives (S)-(-)-NOBIN,1e or a mixture of toluene and ethanol; kinetic resolution of the corresponding imine with various amino alcohols is rather inefficient. An improved procedure relies on the co-crystallization of (±)-NOBIN with 0.5 equiv of N-benzylcin-chonidinium chloride from acetone, which gives (R)-( + )- NOBIN.7 The absolute configuration was determined by CD spectroscopy (namely, by comparison with the spectra of 1,1-binaphthalene-2,2-diol and 2,2-diamino(1,1-binaphthalene)),1b and confirmed by chemical correlation,5 and X-ray analysis.7 An alternative synthesis, starting with (R)-1,1-binaphthalene-2,2-diol (BINOL), employs the Hartwig-Buchwald amination (2) of the protected monotriflate (Ar = 4-MeO-C6H4).8 Although less straightforward, the latter protocol has the advantage of avoiding the use of toxic 2-aminonaphthalene.

Drying: standard drying during the work up; not hygroscopic.

Handling, Storage, and Precautions: keep tightly closed, store in a cool dark place; may slowly deteriorate when exposed to direct sunshine and air.

(R)-Dimethyl-NOBIN and its N,N-dialkyl analogues,2 obtained from (R)-NOBIN on reductive amination of the corresponding aldehydes and ketones, respectively, catalyze the Et2Zn addition to aromatic aldehydes (3), affording the (R)-alcohols with up to 88% ee (for PhCHO and dimethyl-NOBIN).2

Imines, derived from methyl esters of amino acids, can be alkylated with PhCH2Br and other good electrophiles, under the phase transfer conditions in the presence of solid NaOH and (S)-NOBIN (10 mol %) in a nonpolar solvent to give unnatural a-alkyl amino acids (4). Best results were obtained for a-methyl-phenylalanine (62% ee).3a,3b Alkylation of the glycine-derived nickel complex under the similar conditions (5), with (R)-NOBIN as catalyst, exhibits very high enantioselectivities (98% ee for phenylalanine and 99.5% ee for DOPA).3c Strong nonlinear effect has been observed for the latter alkylation (NOBIN of 40% ee exhibits the same asymmetric induction as its enantiopure counterpart).3c Furthermore, no second alkylation occurs in this case since the enolization of the primary product is precluded by steric hindrance.

High asymmetric induction has been reported for aldol reaction of ethyl acetate silyl enol ether or methoxypropene (6) catalyzed by a titanium(IV) complex of the (R)-NOBIN-derived imine (Carreira ligand).9 Methoxy olefins react with a similarly high enantioselectivity as their silylated counterparts.9

NOBIN can serve as a starting material for the preparation of various N-monoalkyl- and N,N-dialkyl-NOBIN analogues via reductive amination. Aldehydes react with NOBIN in the presence of NaBH4 and H2SO4 to give dialkyl amino analogues, whereas ketones afford monoalkylated products (7).2 Hartwig-Buchwald arylation of NOBIN produces N-monoaryl derivatives (8).10 Alternatively, N-aryl-NOBIN derivatives can be prepared by amination of the protected monotriflate derived from BINOL with various aromatic and heteroaromatic amines.8

Employing the Newman-Kwart rearrangement, NOBIN and dimethyl-NOBIN can be converted into the corresponding (S)-aminothiol without racemization (9).11

New aminophosphine ligands (MAP) have been obtained from the triflate derived from dimethyl NOBIN by Pd(0)-catalyzed coupling (10)12 and applied in asymmetric synthesis.

O-methyl-NOBIN and the corresponding imines have been prepared by Curtius rearrangement (11);13 the imines were employed in the asymmetric transfer of the Fe(CO)3 unit to form planar-chiral diene complexes.13c

5,5,6,6,7,7,8,8-octahydro-NOBIN (H8-NOBIN)14 has been prepared by partial reduction of NOBIN with Ni-Al alloy15 in a dilute aqueous alkaline solution (12) and utilized as starting material for the synthesis of the corresponding aminophosphine14 and as an O,N-ligand for Et2Zn addition to aldehydes.16

The NOBIN derivative, prepared by the Cu(II)-mediated coupling of 2-aminonaphthalene with 3-hydroxy-2-naphthoate, exhibits a solid-state BAL2 intermolecular migration of the ester CH3 group to nitrogen (13).17

1. (a) Smrcina, M.; Lorenc, M.; Hanus, V.; Kocovský, P., Synlett. 1991, 231. (b) Smrcina, M.; Lorenc, M.; Hanus, V.; Sedmera, P.; Kocovský, P., J. Org. Chem. 1992, 57, 1917. (c) Smrcina, M.; Poláková, J.; Vyskocil, s.; Kocovský, P., J. Org. Chem. 1993, 58, 4534. (d) Smrcina. M.; Vyskocil, s.; Máca, B.; Polásek, M.; Claxton, T. A.; Abbott, A. P.; Kocovský, P., J. Org. Chem. 1994, 59, 2156. (e) Smrcina, M.; Vyskocil, s.; Polívková, J.; Poláková, J.; Kocovský, P., Collect. Czech. Chem. Commun. 1996, 61, 1520.
2. (a) Vyskocil, s.; Jaracz, S.; Smrcina, M.; stícha, M.; Hanus, V.; Polásek, M.; Kocovský, P., J. Org. Chem. 1998, 63, 7727. (b) Vyskocil, s.; Meca, L.; Kubista, J.; Malo&nbreve;, P.; Kocovský, P., Collect. Czech. Chem. Comm. 2000, 65, 539.
3. (a) Belokon, Y. N.; Kochetkov, K. A.; Churkina, T. D.; Ikonnikov, N. S.; Vyskocil, s.; Kagan, H. B., Tetrahedron: Asymmetry 1999, 10, 1723. (b) Belokon, Y. N.; Kochetkov, K. A.; Churkina, T. D.; Ikonnikov, N. S.; Chesnokov, A. A.; Larionov, O. V.; Singh, I.; Parmar, V. S.; Vyskocil, s.; Kagan, H. B., J. Org. Chem. 2000, 65, 7041. (c) Belokon, Y. N.; Kochetkov, K. A.; Churkina, T. D.; Ikonnikov, N. S.; Larionov, O. V.; Harutjunan, S. R.; Vyskocil, s.; North, M.; Kagan, H. B., Angew. Chem., Int. Ed. 2001, 40, 1948.
4. Mahmoud, H.; Han, Y.; Segal, B. M.; Cai, L., Tetrahedron Asymmetry 1998, 9, 2035.
5. (a) Ding, K.; Xu, Q.; Wang, Y.; Liu, J.; Yu, Z.; Du, B.; Wu, Y.; Koshima, H.; Matsuura, T., Chem. Commun. 1997, 693. (b) Vyskocil, s.; Smrcina, M.; Lorenc, M.; Hanus, V.; Polásek, M.; Kocovský, P., Chem. Commun. 1998, 585.
6. Carreira, E. M., personal communication.
7. Ding, K.; Wang, Y.; Yun, H.; Liu, J.; Wu, Y.; Terada, M.; Okubo, Y.; Mikami, K., Chemistry-Eur. J. 1999, 5, 1734.
8. Singer, R. A.; Buchwald, S. L., Tetrahedron Lett. 1999, 40, 1095.
9. (a) Carreira, E. M.; Singer, R. A.; Lee, W.; J. Am. Chem. Soc. 1994, 116, 8837. (b) Carreira, E. M.; Lee, W.; Singer, R. A., J. Am. Chem. Soc. 1995, 117, 3649. (c) Singer, R. A.; Carreira, E. M., J. Am. Chem. Soc. 1995, 117, 12360.
10. Vyskocil, s.; Smrcina, M.; Kocovský, P., Tetrahedron Lett. 1998, 39, 9289.
11. Smrcina, M.; Vyskocil, s.; Polívková, J.; Poláková, J.; Sejbal, J.; Hanus, V.; Polásek, M.; Verrier, H.; Kocovský, P., Tetrahedron: Asymmetry 1997, 8, 537.
12. Vyskocil, s.; Smrcina, M.; Hanus, V.; Polásek, M.; Kocovský, P., J. Org. Chem. 1998, 63, 7738.
13. (a) Hattori, T.; Shijo, M.; Kumaga, S.; Miyano, S., Chem. Express 1991, 6, 335. (b) Hattori, T.; Hotta, H.; Suzuki, T.; Miyano, S., Bull. Chem. Soc. Jpn. 1993, 66, 613. (c) Knölker, H.-J.; Hermann, H., Angew. Chem., Int. Ed. Engl. 1996, 35, 341. (d) Hungerhoff, B.; Metz, P., Tetrahedron 1999, 55, 14941.
14. Wang, Y.; Guo, H.; Ding, K., Tetrahedron: Asymmetry 2000, 11, 4153.
15. Guo, H.; Ding, K. L., Tetrahedron Lett. 2000, 41, 10061.
16. Guo, H.; Wang, Y.; Ding, K., Chin. J. Chem. 2001, 19, 52.
17. Smrcina, M.; Vyskocil, s.; Hanus, V.; Polásek, M.; Langer, V.; Chew, B. G. M.; Zax, D. B.; Verrier, H.; Harper, K.; Claxton, T. A.; Kocovský, P., J. Am. Chem. Soc. 1996, 118, 487.

Pavel Kocovský

University of Glasgow, Glasgow, UK

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