Synthesis ofN-Fused “Lactendiynes”

10-Membered Azaenediyne Fused to a Benzothiophene through the Nicholas Macrocyclization: Synthesis and DNA Cleavage Ability

“…31,32,36 Only single example of the Nozaki cyclization has been also reported for the azaenediyne system fused to a -lactam ring. 41 Of special note is that the alkylation-type macrocyclization was used for Co complexes in the synthesis of 9-membered azaenediynes. 42 Thus, it is quite unexpected that the Nicholas macrocyclization technique has never been employed for the construction of these useful strained cyclic aza-alkynes.…”

Development and applications of highly selective palladium-catalyzed monocoupling reactions of (cyclo)alkenes and 1,3-alkadienes bearing two or three electrophilic sites and bis(enol triflates) with terminal alkynes

“…Moreover, a protocol very similar to that employed to prepare compounds 49 was used to prepare lactenediynes 51 from 2e and 1-alkyne 50 (Figure 4). 46 In 1994, Chemin and Linstrumelle reported several examples of Pd/Cu-catalyzed sequential alkynylation reactions of (Z)-and (E)-1,2-dichloroethene that provided chloroenynes and then enediynes 47 and described that both the nature of the catalyst and the amine were critical for the success of the couplings. In particular, (E)-1-chloro-1-ene-3-ynes 4 were stereospecifically prepared in high yields by the reaction of 1-alkynes with 5 equiv of (E)-1,2-dichloroethene (3) in benzene at room temperature in the presence of 5 mol% Pd(PPh 3 ) 4 , 10 mol% CuI and 2 equiv of piperidine (Scheme 15).…”

“…More recently, (Z)-enynylbenzofuran 142 was synthesized in two steps from (Z)-enediyne 52c (Scheme 53), 93 which was prepared in 36.2% overall yield by sequential Pd/Cucatalyzed alkynylation of 1 with 1-hexyne and trimethylsilylacetylene, according to the procedure of Chemin and Linstrumelle. 46 Desilylation of 52c with K 2 CO 3 in MeOH gave compound 142, which was coupled with 2iodophenol in Et 2 O in the presence of n-BuNH 2 and catalytic quantities of Pd(PPh 3 ) 4 and CuI to give 143 in 7% yield (Scheme 53). 93 The formation of the benzofuran ring presumably involved a cyclization process, catalyzed by the acidic phenol group, of the Sonogashira-type coupling derivative obtained from 142 and 2-iodophenol.…”