Intramolecular addition reactions Samarium iodide

The reaction of a ketone with an allyl acetate in the presence of samarium iodide catalyzed by palladium (Pd°) has been applied to an intramolecular addition. The keto acetate 546 [prepared from neryl acetate (27 acetate)] was cyclized to l-menthen-4-ol ( 4-terpinenol 547) in 62% yield using 5 mol% of Pd(PPh3)4. Separation of the (+)- and (- )-isomers of 547 has been achieved on Chirasil-Val columns. The synthesis by Delay and Ohloff of optically active l,8-menthadien-4-ol (548) (Vol. 4, p. 511, Ref. 382) encountered difficulties when it was carried out on a larger scale. They then attempted to... 

Since the intramolecular reactions are so much the best, others have linked the alkene and the alkyne by a weak bond that can later be sacrificed. This is the tether strategy you will meet in chapter 36. An N-0 bond is ideal and with the alkyne additionally blocked with a silyl group 124, good yields of Pauson-Khand product 125 and of the amino alcohol 126 could be achieved even with an amine A-oxide as promoter. Samarium(II) iodide was used as the reducing agent.35... 

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