In some embodiments, R 2 and R 3 taken together with the atoms to which they are attached form a 5 or 6 membered carbocycle with at least one sp 3 hybridized carbon and R 4 is cyano, fluoroalkyl, sulfonamidyl, sulfinyl, sulfonyl, sulfoximinyl or fluoroalkylsulfonyl <a href=https://alevitra.mom>comparacion viagra cialis levitra</a>
