Abstract: Rhombohedral system boron nitride is produced by heating a boron material selected from the group consisting of boron oxide, boric acid and an oxygen-containing boron compound capable of forming boron oxide when heated, at a temperature of from 1200.degree. to 2100.degree. C. to vaporize boron oxide and reacting the vaporized boron oxide with hydrogen cyanide or cyanogen gas.

Abstract: A process for preparing cubic boron nitride comprises heating hexagonal boron nitride and magnesium boron nitride at a temperature of at least 1350.degree. C. under a pressure at which the cubic boron nitride is thermodynamically stable, whereby the cubic boron having high strength and high purity can readily be obtainable. Also disclosed is a process for the preparation of magnesium boron useful as a starting material for the above process. This process comprises mixing hexagonal boron nitride and magnesium nitride or metal magnesium in a molar ratio of hexagonal boron nitride/magnesium being at least 0.6, and heating the mixture thus obtained, at a temperature of from 950.degree. to 1250.degree. C. under atmospheric pressure in a non-oxidizing atmosphere, e.g. a nitrogen atmosphere.

Abstract: Novel method optically active oxazaphosphorin derivatives represented by the general formula (I), ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are respectively different from each other and are hydrogen atom(s), lower alkyl group(s), aralkyl group(s), or aryl group(s); and X is a halogen atom. The novel oxazaphosphorin derivative is prepared by reacting an optically active amino alcohol derivative represented by the general formula (II), ##STR2## wherein R.sup.1, R.sup.2 and R.sup.3 are the same as defined above, with a phosphorus compound represented by the general formula (III),POX.sub.3wherein X is the same as defined above.The novel optically active oxazaphosphorin derivatives are useful as intermediates for preparing optically active cyclophosphamide derivatives which are useful therapeutical agents for curing against follicular lymphoadenopathy, lymphosarcomatosis, Hodgkin's disease, lymphosarcoma cell leukaemia, reticulum-cell sarcoma or the like.

Abstract: A novel process for preparing cyclo-1,3,2-oxazaphosphoryl derivatives represented by the formula (II), ##STR1## wherein R.sup.2 and R.sup.3 are respectively a lower alkyl group which may have halogen atom(s) or lower alkane-sulfonyloxy group(s) as substituted group(s) and n is an integer of 2 to 6, by acid cleaving the R.sup.1 --N bond of the compound represented by the formula (I), ##STR2## wherein R.sup.1 is an .alpha.-arylalkyl group, by using a strong acid, the compound represented by the formula (II) being effective as an anticancer agent.

Abstract: A 1,3-conjugated diene compound and a derivative of a butadiene dimer are subjected to an addition reaction over a rhodium compound. The 1,3-conjugated diene compound adds to the derivative in a molar ratio of 1:1. The derivative may be an ester, ether or alcohol. Said derivative is obtained either by reacting a carboxylic acid, an alcohol or a phenol with a butadiene over a palladium catalyst or by hydrolyzing the reaction product.