The distillate, b.p. 75-80°( 0.3 mm.), 0.19 g., was analyzed by n.m.r. spectroscopy, which indicated 46.7 ± 4.1% of IV and 53.3 ± 4.1 % of III.(ti).-To 3.5 g. of iodine and 6.8 g. of potassium iodide in 60 ml. of water was added the sodium salt of XII (from 1.0 g. of XII and 1.73 g. of sodium bicarbonate) in 30 ml. of water. A heavy oil which separated was extracted with ether. The extracts were washed with sodium bisulfite solution until colorless, sodium bicarbonate solution, and water and dried. Removal of ether furnished 1.5 g. (82%) of an undistillable (dec.) noncrystallizable oil which represented the iodolactone (infrared spectrum). Hydrogenolysis with W-2 Raney nickel in ethanol and triethylamine was only partially successful, whereas hydrogenolysis with nickel and sodium bicarbonate completed removal of iodine. Infrared and n.m.r. spectra of the product indicated that it was composed of III and IV; n.m.r. analysis indicated the presence of 54.2 ± 2% III and 45.8 ± 2% IV.1-Cycloheptene-l-acetic Acid (XV) and Cycloheptane-1 '"-acetic Acid (XVI).-Dehydration of the hydroxy ester, obtained in 67% yield by the Reformatsky reaction of cycloheptanone and ethyl bromoacetate, with thionyl chloride furnished a mixture of ,ßand d.v-unsaturated ester; b.p. 71-82°( 1.5 mm.); yield, 51%; infrared bands at 1740 (ester), 1715 (conjugated ester), and 1635 cm.-1 (conjugated double bond) which contained 60% of the /3,7-unsaturated compound (v.p.c.). Hydrolysis gave a mixture of the title compounds, b.p. 110-114 (18 mm.), 74% yield, which was used directly for the following reactions.(A) .-Cyclization of the mixture with dilute sulfuric acidacetic acid for 11 hr. and work-up in the usual manner gave 57% of a neutral fraction, b.p. 68-73°( 0.15 mm.), whose n.m.r. analysis indicated that it was composed of 73.7 ± 1.6% cislactone III and 26 ± 1.6% ¿rans-lactone IV.(B) .-Iodolactonization of the mixed acids yielded 26% of a noncrystallizable oil which decomposed on attempted distillation but was a mixture of iodolactones (infrared spectrum). W-2 Raney nickel hydrogenolysis in ethanol with sodium bicarbonate gave a mixture of lactones III and IV, b.p. 88-92°( 0.6 mm.),
Communications to the Editor Vol. 79 gifts3 456•7 of synthetic isomers of sphingosine made it possible to settle this point in the experiments shown in Table II in which "active ceramide'' is identified as N-acetyl-DL-threo-/TOMS-sphingosine.The possible biological significance of the fact that the enzymatically active form of sphingosine possesses the threo rather than the expected erythro configuration is currently being investigated. (6) Gift of Dr. Paul O'Connell and the Upjohn Company. (7) Gift of Prof. C. A. Grob and the Ciba Company.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.