Question

The anti-tumor compound maytansine was originally isolated from the Ethiopian shrub Maytenus serrata. Development of a multistep synthesis of maytansine involved compound 1 as a key precursor. (Tet. Lett. 1975, 31, 2643-2646.) Propose an efficient synthesis of 1 starting with acetylene, acetone, and formaldehyde as the only sources of carbon atoms. Select the appropriate reagents for each step. Enter only one letter in each enter field. step 1 step 2 Ho OH step 3 OH OH step 4

Answer 1

"Algae is treated with 2 equivalents of strong base Na NH_2 which will the alkynes to form acetylene ions. These ions attack the to form alcohols. The alkynes is converted into is allege by reduction with catalyst which is a mixture of pd, CaCO_3, Pb salts and "" The is protected by using acetone in presence of acid."