2 ’- ferrocenyl ethylamine

To a mixture of vinyl bromide (40 mmol) and the catalyst dichloro-[(R)-Af,N-dimethyl-l-[(.S)-2-(diphenylphosphino)ferrocenyl]ethylamine]-palladium(n) (0.2 mmol) was added an ethereal solution of [a-(trimethyl-silyl)benzyl]magnesium bromide (0.6-1 m, 80 mmol) at —78 °C. The mixture was stirred at 30 °C for 4 days, and then cooled to 0 °C and hydrolysed with dilute aqueous HC1 (3 m). The organic layer was separated, and the aqueous layer was re-extracted with ether. The combined organic extracts were washed with saturated sodium hydrogen carbonate solution and water, and dried. Concentration and distillation gave the chiral allylsilane (79%, 66% ee), b.p. 55°C/0.4mmHg. 

Rapid aminations of 1-bromonaphthalenes with piperidine under microwave irradiation were reported by Hamann using Pd2(dba)3/rac. PPFA (N,N-dimethyl-1-[2-(diphenylphosphanyl)ferrocenyl]ethylamine) precatalyst in combination with NaO-t-Bu in toluene at 120 °C (Scheme 92) [97]. Typically, reactions performed under conventional heating at 120 °C (oil bath) were still progressing after 16 h and were essentially complete by 24 h, whereas the microwave reactions appeared to be finished after 10 min. The same reaction conditions were also useful to functionalize 5- and 8-bromoquinolines with anilines and aliphatic amines (Schemes 93 and 94). Remarkably, no product formation was observed with 5-bromo-8-cyanoquinoline and 5-bromo-8-methoxyquinoline under conventional heating for 24 h at the same temperature, while the desired 5-aminoquinolines were smoothly obtained under microwave irradiation in a reaction time of only 10 min. 

Early work involving simple alkenes employed the catalyst dichloro (y )-AUV-dimethyl-l-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine palladium(II), 1 (often abbreviated to Pd-Cl2[(i )-(S)-PPFA]). When applied to the hydrosilylation of norbornene with trichlorosilane, it yielded an adduct which was converted to a pentafluorosilicate and thence to the alcohol 2 in 25% overall yield and with 50% ee26. 

BIS(CYCLOHEXYL ISOCYANIDE)GOLD(I) f, 2-BIS(DIPHENYLPHOSPHINO)FERROCENYL]ETHYLAMINE 115... 

Asymmetric AUylation. Asymmetric allylation of p-diketones using the palladium analog of (1) has been described. Higher enantioselectivity can be achieved in this case using ferrocenylamines with a modified alkyl side chain. For synthetically useful ferrocenylamine complexes of other metals, see (R)-N-[2-(N,N-Dimethylamino)ethyl]-N-methyl-l-[(S)-l, 2-bis-(diphenylphosphino)ferrocenyl]ethylamine. 

Preparative Methods can be prepared in two steps from commercially available (—)-(f )-A, Af-dimethyl-l-[(S)-l, 2-bis(diphenylphosphino)ferrocenyl]ethylamine. 

Related Reagents. 2,2 -Bis(diphenylphosphino)-l,l -bina-phthyl 2,3-Bis(diphenylphosphino)butane (R)-N-[2-(NJ -Dimc-thylamino)ethy l]-A -methy 1-1 -[(5)- l, 2-bis(diphenylphosphino)-ferrocenyl]ethylamine (lS,9S)-l,9- Bis[(f-butyl)dimethylsilyl-oxy]methyl -5-cyanosemicorrin (/ )-NA-Dimethyl-l-[(5)-2-(diphenylphosphino)ferrocenyl]ethylamine. 

Bis(cyclohexyl isocyanide)gold(I) Tetrafluoroborate-(/J)-A/-[2-(A/, N-Dimethylamino)ethyl]-N-methyl- 1-(S)-1, 2-bis(diphenylphosphino)ferrocenyl]ethylamine, 115 C41H50O4... 

Chiral ferrocenylphosphines were first prepared by Hayashi and Kumada in 1974 [7], The asymmetric ortho-lithiation of optically resolved iV,iV-dimethyl-l-ferrocenyl-ethylamine 1 with butyllithium reported by Ugi and coworkers [8] (see Chapter 4) was conveniently used for their preparation. The addition of diphenylchloro-phosphine to the ortho-lithiated ferrocene 2 generated from (/ )- gave R)-N,N-dimethyl-l-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine ((/ )-(S)-PPFA 3a) in 60 — 70% yield (Scheme 2-1) [9], The first R) designates the carbon central chirality... 

Planar chiral compounds should also be accessible from the chiral pool. An example (with limited stereoselectivity) of such an approach is the formation of a ferrocene derivative from a -pinene-derived cyclopentadiene (see Sect. 4.3.1.3 [81]). A Cj-symmetric binuclear compound (although not strictly from the chiral pool, but obtained by resolution) has also been mentioned [86]. Another possibility should be to use the central chiral tertiary amines derived from menthone or pinene (see Sect. 4.3.1.3 [75, 76]) as starting materials for the lithiation reaction. In these compounds, the methyl group at the chiral carbon of iV,iV-dimethyl-l-ferrocenyl-ethylamine is replaced by bulky terpene moieties, e.g., the menthane system (Fig. 4-2 le). It was expected that the increase in steric bulk would also increase the enantioselectivity over the 96 4 ratio, as indicated by the results with the isopropyl substituent [118]. However, the opposite was observed almost all selectivity was lost, and lithiation also occurred in the position 3 and in the other ring [134]. Obviously, there exists a limit in bulkiness, where blocking of the 2-position prevents the chelate stabilization of the lithium by the lone pair of the nitrogen. 

Dichloro((/ )-AA -dimethyl-l-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine) palladium(II), [(R)-(5)-PPFA]PdCl2, is an efficient catalyst for the asynunetric hydrosilylation of styrene and norbomadiene with HSiCl3, which gives rise to (S)-a-phenyl-ethyltrichlorosilane and (lR,25,45)-norbomyltrichlorosilane, respectively, in good yields ... 

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