Condensation of methyl l,2,3,4,5,6-hexahydroazepino[4,5-b]indole-5-carboxylate (6) with 5-chloro-2-ethyl-4hydroxypentanal lactol ( 14) yielded the 14a-and 14/3-hydroxyvincadifformines (8a,b) in an epimeric ratio which was solvent dependent. On condensation of the indoloazepine 6 with 4,5-epoxy-2-ethylpentanal (9) the same compounds were formed together with a (hydroxymethyl)-D-norvincadifformine, 10, as the major product.Dehydration of 14d-hydroxyvincadifformine (8a) readily gave tabersonine (1), while 14a-hydroxyvincadifformine (8b) could only be dehydrated by carbamate pyrolysis. The latter compound (8b) and the (hydroxymethyl)-D-norvincadifformine 10 could be converted to vincadifformine (18) through the chloromethyl derivative 16. Condensation of the indoloazepine 6 with the epimeric 4,5-dichloro-2-ethylpentanals ( 19) also gave the (chloromethyl)-D-norvincadifformine 16 and 14/3-chlorovincadifformine (20). Dehydrohalogenation of the latter compound provided a third sequence to tabersonine (1). A synthesis of the C-20 epimeric pandolines (2a,b) from 5-chloro-4-ethyl-4-hydroxypentanal lactol ( 22) similarly allowed control of the C-20 epimeric product ratio through its solvent dependence.

The hydroxymethylation of the ester enolate derived from the ester (2) provided the hydroxymethylated adducts (3) snd (4) both of which have been successfully converted into 1 2-hydroxymethylprostaglandin F,, methyl ester(1).INTEREST in C-12 substituted prostaglandins has culminated in the synthesis of 12-methyl prostaglandin^,^ 1 2-fluoro-PGF,, methyl ester,, and 11-deoxy-12-hydroxy-rneth~l-PGE,.~ We report the total synthesis of 12hydroxymethylprostaglandin F,, methyl ester [ 12-hydroxymethyl-PGF,, methyl ester (l)] from the previously described bicyclo[2.2. llheptane derivative (2) .4

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