Abstract: A compound of formula 1, or a pharmaceutically acceptable salt thereof, wherein: X is S, O, or NH; “a” is a single bond; or “a” is a double bond and one of R3 and R4, and one of R5 and R6 are absent; R1 is H; or is selected from an alkyl group, a cycloalkyl group, a heteroaryl group, an aralkyl group, CO-alkyl, SO2-alkyl, CO2R13 and an aryl group, each of which optionally contains one or more heteroatoms, and is optionally substituted with one or more groups selected from R8 and R9; R2 is H, R8, or an alkyl group optionally substituted with one or more R8 groups; R3, R4, R5, and R6 are each independently selected from H, R8, an alkyl group and an alkenyl group, wherein said alkyl and alkenyl groups are optionally substituted with one or more R8 groups; or R3 and R4, and/or R5 and R6 together represent ?O; R7 is H, R8, NH(CH2)nR9, CO(CH2)nR9, NHCO(CH2)nR9, O(CH2)nR9, or an alkyl or phenyl group, each of which is optionally substituted with one or more groups selected from R8 and R9; R8 is OR10, NR10R11, ha

Abstract: A compound of formula 1, or a pharmaceutically acceptable salt thereof, wherein: X is S, O, or NH; “a” is a single bond; or “a” is a double bond and one of R3 and R4, and one of R5 and R6 are absent; R1 is H; or is selected from an alkyl group, a cycloalkyl group, a heteroaryl group, an aralkyl group, CO-alkyl, SO2-alkyl, CO2R13 and an aryl group, each of which optionally contains one or more heteroatoms, and is optionally substituted with one or more groups selected from R8 and R9; R2 is H, R8, or an alkyl group optionally substituted with one or more R8 groups; R3, R4, R5, and R6 are each independently selected from H, R8, an alkyl group and an alkenyl group, wherein said alkyl and alkenyl groups are optionally substituted with one or more R8 groups; or R3 and R4, and/or R5 and R6 together represent ?O; R7 is H, R8, NH(CH2)nR9, CO(CH2)nR9, NHCO(CH2)nR9, O(CH2)nR9, or an alkyl or phenyl group, each of which is optionally substituted with one or more groups selected from R8 and R9; R8 is OR10, NR10R11, h

Abstract: The invention relates to the fabrication of IMPATT diodes. The invention discloses a specific sequence of steps and enables diodes to be mass produced without technological variations.