| 摘要 |
A method for synthesizing L-ribose (1) and 2-deoxy L-ribose (12) from inexpensive D-ribose (2) is provided. The 5-O-trityl ribose (3) (prepared in 70 % yield from D-ribose) is reduced with borohydride to give the tetrol (4), which is then peracetylated to the tetraacetate (5). Hydrolysis of the trityl ether followed by Swern oxidation affords the aldehyde (7) via the alcohol (6). This aldehyde is a protected form of L-ribose, being L-ribose 2,3,4,5,-tetraacetate. Mild basic hydrolysis of the acetate affords L-ribose itself (1), thus ending an efficient six-step synthesis of (1) from (2) which proceeds in 39 % overall yield. In a second aspect of the invention, L-ribose is converted into the beta -selenophenyl ribofuranoside (10) via the tetraester (9) in 71 % isolated yield for the four steps. Treatment of (10) with tributylstannane and AIBN furnishes in 84 % yield the tribenzoyl 2-deoxy-L-ribofuranoside (11) which, on basic hydrolysis, gives 2-deoxy L-ribose (12) in high yield. In a third aspect of the invention, L-arabinose (13) is converted into 2-deoxy L-ribose (12) via the arabinopyranosyl bromide (14), via similar reductive rearrangement with tributylstannane to give the 2-deoxy ribopyranose tribenzoate (16). Hydrolysis yields 2-deoxy L-ribose. In a third aspect of the invention, L-arabinose is converted into 2-deoxy L-ribose by an alternate route. |
