Intramolecular reactions Tsuji-Trost reaction, allylation, carbon

The water soluble vitamin (+)-biotin was synthesized by M. Seki and co-workers from L-cysteine in only 11 steps using inexpensive reagents and mild reaction conditions." The key ring forming step was an intramolecular allylic amination Tsuji-Trost reaction using a nitrogen nucleophile) of a cis allylic carbonate. As expected with a soft nucleophile, the allylation took place with an overall retention of configuration. 

The formation of chromane derivatives has also been realised in the palladium catalyzed intramolecular nucleophilic substitution of allyl carbonates (Tsuji-Trost reaction). In most cases the reaction is accompanied by the formation of a new centre of chirality. Using Trost s chiral ligand the ring closure was carried out in an enantioselective manner. The asymmetric allylation of the phenol derivative shown in 4.20. was achieved both in good yield and with excellent selectivity.23... 

More recently, in 2003, Sorensen demonstrated an impressive, scalable synthesis of cytotoxic natural product (+)-FRl 82877 34, which employed an intramolecular Tsuji-Trost allylation reaction to prepare the 19-membered macrocycle 33. Exposure of allylic carbonate 32 to 10 mol% palladium catalyst under high dilution formed the key bond in good yield and complete diastereoselectivity. This key intermediate was subsequently converted to (+)-FRl 82877 34 via an intramolecular Diels-Alder reaction. 

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