In the preceding paper (1) it was shown that 1,3,5-hexatriene might serve as the basis of a general synthetic method for condensed ring compounds of angular construction, such as steroids, since it was possible to secure, as the principal product of its addition to a cyclohexene, a derivative of 1-vinyloctahydronaphthalene with the annular double bond probably in the 2,3-position. The utility of this intermediate in the synthesis of angular polycyclic compounds would depend on its ability to isomerize to a 1-vinyl-l-octalin which could then add a dienophile. Before the feasibility of this procedure could be tested, we had observed that a 1,5-diene-3-yne can add two molecules of dienophile to give a crystalline product and it has now been found that this addition proceeds in the manner required for the synthesis of compounds of the type sought. In 1933 Blomquist and Marvel (2) found that both 4,7-di-n-propyl-3,7-decadiene-5-yne and 6,9-dimethyl-5,9-tetradecadiene-7-yne added two moles of maleic anhydride in boiling xylene. Since the products of reaction did not crystallize, the solution in xylene was heated with aqueous alkali. Neutralization of the alkaline extract gave products with the composition RéCuHioOs but, as these were amorphous, no attempt was made to characterize them further.We have now heated 2,5-dimethyl-l, 5-hexadiene-3-yne (I) with maleic anhydride at 130°. From the reaction-mixture a crystalline product, CieHuOe, was isolated. If the two moles of maleic anhydride added one after the other in the manner of a Diels-Alder reaction, then III and IV would be the expected structures.2 The intermediate II has not been

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Improved procedures are given for the preparation of a-and ß-D-xylopyranose tetrabenzoates, 2,3,4-tribenzoyl--D-xylopyranosyl bromide and 2,3,4-tribenzoyl-2-hydroxy-D-xylal.The latter compound was found resistant to hydrogenation under the conditions employed for the reduction of its acetyl analog. Revised physical constants for some of the substances are recorded.

Although most of the known naturally occurring steroids are nonbenzenoid, the total synthesis of this type has not yet been accomplished. It should be possible to build up a large variety of such compounds by means of successive Diels-Alder diene additions. The Diels-Alder reaction has the great advantage that it always proceed^stereoselectively to give polycyclic compounds with cis configuration at the ring junctions, and furthermore two successive additions lead exclusively to one of the possible cis,cis isomers (1). Dane and collaborators (2) have employed this reaction for the synthesis of steroids containing one benzene ring, and Cook and Lawrence (3), Meggy and Robinson (4), Butz (5), Goldberg, and Müller (6), and others have reported applications of the reaction which might be extended to the synthesis of steroids.We have explored some of the possibilities making use of compounds which contain an open chain of six carbon atoms as the basis of the synthesis. From these, the angular tetracyclic skeleton of the steroids might be built up by successive diene additions according to the schemes in diagrams A, B, and C, in which the broken lines represent new carbon-tocarbon links. 1,3,5-Hexatriene, 1,3-hexadien-5-yne, 1,5-hexadien-3-yne, and their derivatives would be examples of six-carbon chains potentially capable of adding successively two molecules of dienophile.3 We have found that both 1,3,5-hexatriene and 2,5-dimethyl-l, 5-hexadien-3-yne form adducts of interest in this connection. This paper will present only the results obtained with hexatriene and a single dienophile, 1,4-naphthoquinone.

Pure pentanol-3 was required in large quantity for work in progress in this Laboratory. Since the physical constants for the carbinol reported in the literature1 show wide disagreement, a study was made on the purity of material synthesized in the laboratory and that obtained from Sharpies Solvents Corporation.Propionaldehyde, b. p. 48.0°at 736 mm., re20D 1.3636, was prepared by dehydrogenation of re-propyl alcohol with a copper catalyst. It was treated in four 8-mole lots with ethylmagnesium chloride in anhydrous ethyl ether. The crude product obtained in 67% yield after distillation through a column of approximately 25 theoretical(1) Brunei,