6762
?here y 5 $/a. For the values a = 2.420& b = 0.486 A, X 5000 A, and it( = 0.18 (for 6328 A),ll the CID and A, components are found to be A, 0.62 X 0.41 X These estimates apply only to gaseous samples; in liquids a significant reduction in Rayleigh scattering occurs through interference, the isotropic contribution being suppressed much more than the anisotropic contribution. These Rayleigh CID components of hexahelicene are disappointingly small; in solution they will be even smaller due to the Rayleigh intensity from the solvent and could probably not be detected at present. The calculated Rayleigh CID of a biphenyl twisted at 45 O is rather larger (A, 1.3 X A, 0.6 X 10-4).5 In contrast, the calculated specific rotation (using the dynamic coupling model) of the twisted biphenyl (863 ") is rather smaller than that of hexahelicene (2650°).9 This is because each pairwise CID contribution is "weighted" by a corresponding polarizability, whereas each pairwise optical rotation contribution is purely additive. Thus a molecule with a large specific rotation will not necessarily show a large Rayleigh CID. Raman CID's associated with certain normal vibrational coordinates of hexahelicene should be rather larger than the Rayleigh CID, but a detailed analysis will take some time. Acknowledgment. I thank Professor A. D. Buckingham for discussion.
-
-
ethanol was produced (96 %) 2-(2'-ch1oroethoxy)ethyl 2'-tetrahydropyranyl ether, bp 87-88 " (0.5 mm), which with sodium hydroxide, butanol, and optically pure (S)- and (R)-2,2'-dihydroxy-l, 1'-binaphthy12 (1) at reflux for 20 hr gave pyranyl ethers that by conventional procedures were converted to ditosylates, ( 9 - 4 and (R)-4, respectively (Chart I ) . Treatment Chart I
-
-
(1 1) N. J. Bridge and A. D. Buckingham, Proc. Roy. Soc., Ser. A , 295, 334 (1966).
L. D. Barron Utiicersity Chemical Laboratory Cambridge, CB2 1E W , Englaud Received July 11, 1974
Compd Mp, no. R R' "C (S)-12H H 207-208 (R)-12H H 207-208 m)-23 CH,OH H 192-195 (R)-34CH3 H 202-204 (S)-44 H (CH2CHz0)2Ts Oil (R)-4 H (CH*CH20)2Ts Oil a c, 1.0. Sodium line.
[ a I z 5 ~ ~Sol~, deg vent0
-34.3* +34.1' +64.1 +30.2 -30.7 +31
Yield,
(CH&O Ref 2 (CH2)rO Ref 2 (CH&O Ref 3 CHC13 25 (CH2)*070 (CH&O 68
of (R)-3 with (R)-4 and potassium hydroxide in T H F and water at reflux for 100 hr gave (RR)-8. Similarly, (S)-4 and (S)-1 gave (SS)-5. and (R)-4 and (R)-1 gave (R,R)-5. Reaction of (R)-4 with optically pure (R)-z3 gave (R,R)-6, which with SOCI, gave (R,R)-7, which with LAH gave (R,R)-8 (Chart 11). The known absolute Chart I1
Models for Chiral Recognition in Molecular Complexation' Sir : Optically pure host compounds 5 2 and 8 have been examined for their abilities to complex selectively and make extractable from water into chloroform the enantiomers of a-amino ester hexafluorophosphate salts as guest compounds. Racemic 3,3 '-bishydroxymethyl-2,2'-dihydroxy-l, 1 '-binaphthyl (2)3 with hydrogen bromide in glacial acetic acid gave (90%) 3,3'bisbromomethyl-2,2'-dihydroxy-l,l'-binaphthyl, mp 2 1 1-2 13 O dec. With LAH, the bromo compound gave (87%) (=t)-3,4 mp 204-205". Optically pure (R)-34 was obtained (25% overall) by resolution of the cinchonine salt of the phosphoric acid diester4 of (1k)-3.~ From dihydropyran and 2-(2'-ch1oroethoxy)(1) This work was supported by a grant from the National Science Foundation, GP33533X, and by the U. S. Public Health Service, Research Grant No. GM12640-10 from the Department of Health, Education and Welfare. (2) E. P. Kyba, I
