IONIC HYDROGENATION OF CHIRAL (ALPHA-HYDROXYALKYL)FERROCENES - DIFFERENT STEREOCHEMISTRY FOR THEIR DIASTEREOMERIC 2-((N,N-DIMETHYLAMINO) METHYL) DERIVATIVES - X-RAY DETERMINATION OF THE RELATIVE CONFIGURATIONSOF REDUCED PRODUCTS

This paper describes the ionic hydrogenation of (pR,3R*,4S*)-and )-3- (2-((N,N-dimethylamino)methyl)ferrocenyl)-4-(4 -methoxyphenyl)hexan-3- ols (1 and 2, respectively, in racemic and optically active series). T hese compounds are the keys in the synthesis of ferrocene derivatives possessing potentially hormonal properties. In this reaction, trifluor oacetic acid was used as the protonating reagent and sodium borohydrid e as the reducing agent. In each case, the reduction leads exclusively to the formation of only one compound. We observe for 1 a selective a ttack of the hydride on the same side as the leaving group and on the opposite side for 2, leading to reduced products 3 and 4 as (pS,3S*,4 R)- and )-3-(2-((N,N-dimethylamino)methyl)ferrocenyl)-4-(4 -methoxyph enyl)hexane, respectively. The relative configurations of 3 and 4 were unambiguously determined by X-ray diffraction analysis of the methyla mmonium iodides 7 and 8 derived from 3 and 4 (through the correspondin g phenols 5 and 6). 7 crystallizes in the monoclinic P2(1) space group with half of a molecule of methanol and one-fourth of a molecule of a cetone (a = 7.350(1) angstrom, b = 27.721(7) angstrom, c = 14.161(2) a ngstrom, beta = 97.42(1)-degrees, and V = 2861(5) angstrom3) with Z = 4. 8 crystallizes in the monoclinic P2(1)/a space group with one hydro gen-bonded molecule of water (a = 10.180(2) angstrom, b = 15.429(2) an gstrom, c = 17.517(3) angstrom, beta = 104.53(1)-degrees, and V = 2663 (9) angstrom3) with Z = 4.