Phenol → HCID 21107315, compound

Participants

Reaction Steps

The 3,4-dihydro-2H-pyrano[2,3-f]quinolin-3-amine 1b is prepared according to Scheme III. The commercially available 5-hydroxyquinoline 13 is first protected with an allyl group, and the resulting 5-allyloxyquinoline 14 subjected to Claisen rearrangement by heating in p-xylene to generate 6-allyl-quinolin-5-ol 15. The resulting phenol is protected with a suitable protecting group, such as benzyl, and the resulting product 16, 6-allyl-5-benzyloxy-quinoline converted to the 3-(5-benzyloxy-quinoline-6-yl)-propane-1,2-diol 17 using the Sharpless Catalytic Asymmetric Dihydroxylation reagent, AD-mix-α. The diol is then converted to the bromoacetate 18 upon heating in 30% HBr in acetic acid, simultaneously cleaving the benzyl protecting group. Cyclization to 19 is achieved under basic conditions using sodium hydride. Cleavage of the acetyl group under basic conditions produced 20, 3,4-dihydro-2H-pyrano[2,3f]quinolin-3-ol quantitatively. The tosylate 21 is then generated using p-toluenesulfonyl chloride in pyridine, and converted to the azide 22 with sodium azide in DMF. The azide is finally reduced by treatment with triphenylphosphine in THF-H2O to provide the 3,4-dihydro-2H-pyrano[2,3-f]quinolin-3-amine 1b suitable for the preparation of some of the derivatives claimed in this invention.

Provenance & Evidence