Method is provided for cyclization of polyunsaturated substituted acylic or monocarbocyclic initiator group containing compound having an endocyclic double bond with a chalcogen atom in the allylic position of the initiator group and having at least two sites of unconjugated aliphatic unsaturation in the side chain substituent on the ring. The polyunsaturated compound is cyclized in the presence of a strong acid in a protic solvent which is inert to the acid, preferably a hydroxylic solvent. Mild temperatures and varying times are employed. The products are useful primarily as intermediates for naturally occurring and synthetic steroids. By appropriate substitution of the side chain, the steroidial products are provided with the substituent at C-11, which upon cyclization results in the alpha-configuration. By resolution of the intermediates prior to cyclization, optically active steroids can be obtained.
本发明提供了一种用于环化多不饱和取代的无环或单环碳基引发基团含有内环双键和烯丙基位置上具有
硫属原子的化合物的方法,该化合物在环上的侧链取代基中至少有两个非共轭的脂肪族不饱和位点。在具有惰性于酸的质子溶剂中,优选为羟基溶剂的条件下,在强酸存在下环化多不饱和化合物。使用温和的温度和不同的时间。该产品主要用于天然和合成类
固醇的中间体。通过适当的侧链取代,可以在C-11处为类
固醇提供取代基,这在环化后会产生α构型。通过在环化之前分离中间体,可以获得光学活性的类
固醇。