Annulation ring-closing metathesis

Scheme 7.27. Catalytic enantioselective annulations using RCM (ring-closing metathesis).

Holt, D J, Barker, W D, Jenkins, P R, Panda, J, Ghosh, S, Stereoselective preparation of enantiomeri-cally pure annulated carbohydrates using ring-closing metathesis, J. Org. Chem., 65,482-493,2000. 

Ring-closing metathesis has been applied to the preparation of annulated indoles including indolo[2,3-a]carbazoles <05JOC10474> and azepino[4,3-h]indoles <05TL7881>. 

Holt and co-workers applied their ring-closing metathesis strategy for the synthesis of six-, seven-, and eight-membered ring annulated carbohydrate systems to synthesize a number of enantiomerically pure annulated carbohydrate systems containing nine-membered ring... 

The cyclization of o-alkynyl allyl ethers 31 can be promoted not only by plat-inum(II) catalysts [4] but also palladium(O) catalysts (Scheme 27.13) [17]. Penta-cyclic compound 35 were synthesized from bis(allyloxy)bis(alkynyl)benzenes 33 via palladium-catalyzed double annulations to the benzodifuran 34, ring-closing metathesis, and oxidation (Scheme 27.14) [18]. 

---