Abstract: The invention relates to a process for polymerizing block polymers of general formula (I): ##STR1## in which process the following are brought into contact with each other: an ethylenically unsaturated monomer of formula:CYY'(.dbd.CW--CW').sub.a .dbd.CH.sub.2,a precursor compoun of general formula (II): ##STR2## a radical polymerization initiator.

Abstract: "Esters" are synthesized by reacting a nucleophile with a propargyl xanthate advantageously having the formula (I):R.sub.3 --C.tbd.C--CR.sub.1 R.sub.2 --S--CS--Y--R (I)in the presence of at least one acid, Bronsted or otherwise, and at a temperature ranging from 0.degree. to 300.degree. C.; the subject reaction is particularly applicable to a wide variety of chiral organic syntheses.

Abstract: "Esters" are synthesized by reacting a nucleophile with a propargyl xanthate advantageously having the formula (I):R.sub.3 --C.tbd.C--CR.sub.1 R.sub.2 --S--CS--Y--R (I)in the presence of at least one acid, Bronsted or otherwise, and at a temperature ranging from 0.degree. to 300.degree. C.; the subject reaction is particularly applicable to a wide variety of chiral organic syntheses.

Abstract: Novel 23-dihydro-oxazolyl steroids of the formula ##STR1## wherein R.sub.1 is selected from the group consisting of hydrogen and methyl, R.sub.2 is selected from the group consisting of methyl and ethyl, R.sub.3 and R.sub.4 are individually selected from the group consisting of hydrogen and alkyl of 1 to 4 carbon atoms, the A, B, C and D rings may contain 1 to 3 double bonds and may be optionally substituted with one or more members of the group consisting of --OH, protected hydroxyl, .dbd.0, protected keto, halogen alkyl or alkoxy of 1 to 4 carbon atoms and alkenyl and alkynyl of 2 to 4 carbon atoms and the dotted line indicates the optional presence of a second bond useful for the preparation of 20-keto-pregnanes and novel intermediates.

Abstract: A novel nitromethylation composition comprising nitromethane and a catalytic amount of a bifunctional basic catalyst, optionally in an organic solvent, a method of nitromethylating ketonic compounds with said compositions and novel steroids of the formulae ##STR1## wherein R.sub.1 is selected from the group consisting of hydrogen, alkyl of 1 to 4 carbon atoms optionally substituted with an oxygen or nitrogen group or halogen and alkenyl and alkynyl of 2 to 4 carbon atoms, R.sub.2 is alkyl of 1 to 4 carbon atoms and the A,B,C and D rings optionally contain at least one double bond and optionally substituted with at least one member of the group consisting of --OH, .dbd.0, halogen, alkyl and alkoxy of 1 to 4 carbon atoms and alkenyl and alkynyl of 2 to 4 carbon atoms and their use to form the corresponding 21-acetoxy-20-ketocorticosteroids compounds in a simple manner.