Employing the method of asymmetric transformation, the absolute configurations of heterocyclic acids III, IV, Va, and VIIa have been determined. The acids Va and VIIa were chemically correlated with alcohols of known absolute configurations.
A method for determination of absolute configuration of secondary alcohols, based on a modified Horeau's method, has been developed. The ratio of (1R,2'S)- and (1R,2'R)-N-[1-(1-naphthyl)-ethyl]-2-phenylbutanamides (V and VI, respectively) was determined by HPLC on a straight phase. The method was tested on a series of steroid and terpene model compounds and was used in the determination of absolute configuration of 15-ripperten-3α-ol (XV), the defense substance of Nasutitermes nigriceps termites. The sensibility of the determination is 100 nmol of the alcohol.
The absolute configuration of (S)-( + )-3-ethyl-5-methyladamantane-1-carboxylic acid (Ia) and (S)-( + )-1-amino-3-ethyl-5-methyladamantane (!Ia) has been det~rmined by comparison of CD curves of the corresponding ( + )-N-methylthioamide I!d and salicylideneimino derivative lie with curves of the analogous derivatives of (S)-( + )-2-methylbutyric acid and (S)-( + )-2-aminobutane, resp. The absolute configuration has been proved by degradation of the (S)-( +)-acid !a to the amine Ila and comparison of CD curves of its salicylidene derivative lie.*** The molecule of adamantane represents a highly symmetric system ('ld symmetry).The appropriate substitution of this system may lead to compounds of two chirality types. Thus, by substitution at Cc 2 ) and Cc 6 ) carbon atoms a system is formed possessing the axial chirality; 2,6-dichloroadamantane-1,3,5,7-tetracarboxylic acid is the first substance of this type, prepared in the optically active form 1 . Appropriate SUbStitution at C(l)• C(3)• C(S)• and C(7) Carbon atoms Of the adamantane ring system results in substances of a central chirality, as shown for the first time by von Schleyer 2 • The first attempts in this respect to resolve the acids Ia, Ib, and Ic (Stepanov and Baklan 3 ) or to prepare the optically active acid Id (Malfer 4 ) were unsuccessful. Later on, the acid Id was resolved with the use of dehydroabietylamine (Me Kervey 5 ); the thus-obtained acid, though inactive at the D line, afforded by degradation the optically active 1-methyl-7-methylenebicyclo[3.3.1 Jnonan-3-one. When resolved with quinine 6 • 7 , the optical rotation of the acid Id at the D line was [a]~0 -0·36° (chloroform). In the recent time, ( + )-1-amino-3-ethyl-5-methyladamantane has been prepared 8 • In the present paper we wish to report determination of the absolute configuration Part XLVIII in the series Asymmetric Reactions; Part XLVII: This Journal38, 3299 (1973). Present address: Research Institute of Pharmacy and Biochemistry, Prague 9. All the adamantane derivatives prepared in the present work were inactive at the sodium D line but afforded monotonous positive ORD curves in the region of shorter wavelengths. On the basis of this effect, the absolute configuration is ascribed to these derivatives.
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