Patent GB-949642-A (GB)
Title: Metadioxane derivatives of pregnane compounds
IPC: F04B1/08
Filed: 1961-10-27
Abstract: The invention comprises (1) a process for the production of androstano-[16, 17-d]-1, 3-dioxane compounds which comprises reacting a 16b , 20a -dihydroxypregnane compound with an aliphatic or cycloaliphatic compound containing a keto or aldehyde group or containing a group convertible into such a group under the reaction conditions, in the presence of an acid dehydration catalyst; and (2) steroids of the formula: <FORM:0949642/C2/1> wherein R1 is an oxo group or a hydrogen atom and a hydroxyl group or an aliphatic acyloxy group of 2 to 6 carbon atoms, R2 is a hydrogen atom, a hydroxyl group or, together with the elimination of the hydrogen atom at the 4-position, a double bond, R3 is a hydrogen atom or an a - or b -hydroxyl group and R4 and R5 are hydrogen atoms or alkyl or alkoxy groups each containing 1 to 5 carbon atoms (but are not both alkoxy groups or hydrogen atoms) or together represent an alkylene chain. The pregnane starting materials for the above process may contain halogen atoms and/or methyl, ethyl, oxo, epoxy, alkoxy, acyloxy, nitro, thiocyano, mercapto or alkylthio groups as additional substituents in the nucleus, and/or double bonds, and/or hydroxyl groups at positions other than 15 and 21, while suitable carbonyl compounds include alkanones, cycloalkanones, alkanals, formic acid and keto-carboxylic acids and their esters, or derivatives of these compounds e.g. ketals, cyclic ketals and cyanhydrins. Suitable catalysts include mineral, sulphonic and Lewis acids, and inorganic and organic acid chlorides. The dioxane products may be reconverted to diol starting materials by the action of aqueous acids. In examples (1) pregn -5- ene-3b , 16b , 20a -triol and acetone give isopropylidene-16b , 20a -dioxypregn -5- en-3b -ol; (2) 5a -pregnane-3b , 5a , 6b , 16b , 20a -pentol and acetone give isopropylidene-16b , 20a -dioxy-5a -pregnane-3b , 5a , 6b -triol; (3) 5a -pregnane -3b , 16b , 20a -triol and acetone give isopropylidene-16,b  20a -dioxy -5a - pregnan -3b - ol and this is oxidized to the 3-one and is also converted to the 3-acetate which on heating with acetic acid gives 3b -acetoxy-5a - pregnane -16b , 20a -diol; (4) 16b , 20a -dihydroxy-pregn -4- en -3- one and acetone give the isopropylidene dioxy compound; (5) isopropylidene -16b , 20a -dioxy -5a - pregnane -3b , 5a , 6b -triol is similarly prepared; (6) isopropylidene -16b , 20a -dioxy-5a -pregnane-3b , 6b -diol is similarly prepared and is converted to the 6-monoacetate; (7) and (8) similarly are prepared isopropylidene -16b , 20a -dioxy -5a -pregnane -3b , 6a -diol (diacetate prepared) and isopropylidene -16b , 20a -dioxy -5a - pregnane -3b , 5a -diol; (9) and (10) butan -2- one and cyclohexanone replace the acetone of (3), the products being 2-sec-butylidene -16b , 20a -dioxy -5a -pregnan -3b -ol and cyclohexylidene -16b , 20a -dioxy -5a - pregnan -3b - ol respectively; and (11) the product of (1) is converted to isopropylidene -16b , 20a - dioxypregn -4- en -3- one, which on heating with acetic acid gives 16b , 20a -dihydroxypregn -4- en -3- one. A list of further starting materials is also provided.