1 -Ferrocenylethyldimethylamine ( 7) is readily obtained from 1 -ferrocenylethanol by treatment with phosgene and then dimethylamine. The resolution of 7 with (i?)-(+)-tartaric acid is particularly easy and both antipodes are obtained in high yield. Qualitatively the steric course of the lithiation 7 -> 8 is predictable and proceeds with high stereoselectivity (96:4). Subsequent reactions of 8 with trimethylchlorosilane, formaldehyde, or benzophenone produce 9a-c. The quaternization of 9 in the presence of nucleophiles leads to substitution of the dimethylamino group in 9 with complete configurational retention, which is confirmed by nmr and the cycle {9a, 10, 14,13 j. The retention is due to the ease of formation of 11 and its configurational stability under suitable conditions. The reactions presented here provide a basis for convenient, predesignated stereoselective syntheses and

Trigonal-bipyramid structures are indicated for PF6 (1) and CH3PF4 (2) by electron diffraction data,2•3 for (CF3)2PF3 (3) by ir and Raman spectra,4 and for PC12F3 (4) by chlorine nuclear quadrupole resonance *

Ferrocenylethane derivatives with suitable leaving groups [chloro, acetate (9), trimethylammonium (2)] in the a position generally undergo nucleophilic substitutions with complete retention of configuration and are useful for the preparation of a variety of chiral ferrocene derivatives. Stereochemical and kinetic evidence indicates an SnI mechanism via a configurationally stable -ferrocenylethyl carbonium ion intermediate. Departure of the leaving group and entry of the substituting nucleophile involve analogous conformations of the a-ferrocenylalkyl system. Winstein-Grunwald mY analysis of ammonium compound 2 indicates only a very slight solvent effect for solvolysis in this stable carbonium ion system. Chiral ferrocene derivatives3 with the general formula 5 and analogous compounds may serve as asymmetrically inducing amine components4 in stereoselective peptide synthesis by four-component condensations,5 i.e., 3 4, because primary amines related to 3 are not only (1) Stereoselective Syntheses. VIII.(2) (a) National Aeronautics and Space Administration predoctoral fellow, 1969-1971. (b) Postdoctoral associate,

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