The acid-catalyzed cyclization of a pseudogeminally substituted acetyl group and a chloromethyl group of tri-bridged cyclophane 7 , followed by reduction of the carbonyl group afforded (3,](1,2,3,5)cyclophane 3. One-step TosMIC coupling reaction of tetrabromide 12 and subsequent reduction of the carbonyl groups provided an isomer of 3, [3,](1,2,4,5)cyclophane 4.[36](1,2,3,4,5,6)Cyclophane 1 is one of the final target molecules in the field of [3.3] As a strategy for the synthesis of 1, we chose the stepwise approach; stepwise introduction of additional trimethylene bridges into [3,](1,3,5)cyclophane 5[51, as a starting compound, might allow the preparation of the hexa-bridged cyclophane 1 by way of tetra-and penta-bridged cyclophanes, if we succeeded in developing an efficient method for introducing a trimethylene bridge. In our efforts along these lines, we have synthesized the first tetra-bridged Acetylation of 5 with acetyl chloride in CH2C12 at -50°C in the presence of AlC13 afforded monoacetylated compound 6 (71%) with a small amount of a pseudogeminally diacetylated compound (9%). Taking advantage of the directing effect of the acetyl group of 616], we were able to introduce a chloromethyl group into a pseudogeminal position (ClCH20CH3, AlC13, room temp.). In this reaction, however, a mixture of the desired 7a and methyl ether 7b, which was
