Furo[3,4-b]pyran compounds and pharmaceutical uses

A method of inhibiting bone marrow tyrosine kinase (BMX) or Bruton tyrosine kinase (BTK), the method comprising contacting the BMX or the BTK with an inhibitory amount of a compound of the formula:

• wherein
• R1 and R2 may each be H, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, aryl, CO2H, CO2alkyl, or C(═O)alkyl, wherein each alkyl, alkoxy, alkenyl, alkynyl or aryl group may optionally be substituted with OH, NH2, halogen, alkoxy, acyloxy or aryl;
• and
• R3 is H, C1-C6 alkyl, C1-C6 acyl, aryl, benzyl or trialkylsilyl;
• provided that R1 is not CH3 when R2 and R3 are both H or when R2 is H and R3 is acetyl;
• or a pharmaceutically acceptable salt thereof.