2-Tetrahydrodibenzo[b.f] [I ,4]diazocine reacts with paraformaldehyde to give the 5,12-endo-methanoderivative : similar bridged compounds were prepared from aromatic aldehydes, but not ketones. The 5.1 2-endomethano-derivative is comparable to Troger's base in its reactions. The synthesis of N-alkyl-5,6,11 , I 2-tetrahydrodibenzo[b,f] [I ,5]diazocines and N-alkyl-5,6,11 ,I 2-tetrahydrodibenzo[b.f] [I ,4]diazocines by direct alkylation and by acylation and subsequent reduction has been investigated. An N-amino-and an NN'-diaminoderivative of the [I ,5]diazocine were prepared.THE synthesis of Troger's base (5,6,11,12-tetrahydro-2,8-dimethyl-5,1 l-ertdo-methanodibenzo[b,fl [ 1,fjldiazocine) (I; R1 = Me, RZ = R3 = H) from p-toluidine and formaldehyde in acid solution, and the extension of this synthesis to analogues, has been described in a number of papers.l Cooper and Partridge synthesised the 5,6,11,12-tetrahydrodibenzolTb,f]jl,5]diazocines (I1 ; R1 = Me or H, R2 = H), and showed that they reacted with aldehydes and certain other carbonyl compounds to give derivatives of the Troger's base type, the product from (11; R1 = Me, R2 = H) and formaldehyde being identical with Troger's base.