Process for the manufacture of spiro compounds of the steroid series

A process for the manufacture of 17-spiro-(2'-oxacyclopentane) compounds of the general formula ##STR9## wherein R.sub.1 represents a hydrogen atom or a lower alkyl group, which contain a double bond in 5-position and a methyl group in 10-position, or three double bonds in the positions 1,3 and 5(10), and which can contain an additional double bond in the 9(11)-position, which process comprises reacting a 17-oxosteroid of the general formula ##STR10## wherein R.sub.1 ' represents a hydrogen atom, a lower alkyl group or an acyl group, which contains a double bond in 5-position and a methyl group in 10-position, or three double bonds in the position 1,3 and 5(10), and which can contain an additional double bond in the 9(11)-position, with an organometallic compound of the formula

• R.sub.o --(CH.sub.2).sub.3 --M (III)
• wherein M represents a grouping MgX, in which X represents a halogen atom or an alkali metal atom and R.sub.o represents a di-lower alkylamino group, converting, by treatment with a lower alkyl ester of a strong acid, the resultant 17.beta.-hydroxy-17.alpha.-(.gamma.-di-lower alkylaminopropyl) compound of the general formula ##STR11## wherein R.sub.1 and R.sub.o are as defined in formulae (I) and (III), respectively, and which contains a double bond in 5-position and a methyl group in 10-position, or three double bonds in the position 1,3 and 5(10), and which can contain an additional double bond in the 9(11)-position, into the corresponding quaternary tri-lower alkylammonium salt, liberating the corresponding quaternary base with a strong base and heating the latter up to the temperature of decomposition.