TY - JOUR AU - Nakazaki, Atsuo; Kobayashi, Susumu TI - Stereocontrolled Synthesis of Functionalized Spirocyclic Compounds Based on Claisen Rearrangement and its Application to the Synthesis of Spirocyclic Sesquiterpenes and Pyrrolidinoindoline Alkaloids SN - 0936-5214 SN - 1437-2096 PY - 2012 JO - Synlett JF - Synlett LA - EN VL - 23 IS - 10 SP - 1427 EP - 1445 ET - 2012/05/24 DA - 2012/06/05 KW - spirocyclic compounds KW - Claisen rearrangement KW - total synthesis KW - one-pot reaction KW - Ullmann coupling AB - Spirocyclic scaffolds are embedded in many biologically active natural compounds, including candidates for medicines, perfumes and agricultural chemicals. Therefore, the development of efficient synthetic methods directed at those structures is strongly in demand. To this end, we have recently developed synthetic methodologies for two different spirocyclic frameworks, spiro[4.5]decanes and spirocyclic oxindoles, based on the Claisen rearrangement.We have developed the Claisen rearrangement protocol by which bicyclic 2-(alkenyl)dihydropyrans with functionality at the 4-position can be transformed into spiro[4.5]decanes in good-to-excellent yields with excellent stereoselectivities. We applied this method to a concise total synthesis of several biologically active spirocyclic sesquiterpenes.Related Claisen rearrangement in alkenyl pyranoindole systems can also be achieved. Thus, a one-pot intramolecular Ullmann coupling (IUC)/Claisen rearrangement sequence from 2-iodoindoles was found to provide spirocyclic oxindoles in good yields with excellent stereoselectivities. We applied this sequence to the synthesis of pyrrolidinoindoline alkaloids.1 Introduction2 Reported Claisen Rearrangement of 2-(Alkenyl)dihydro­pyran Systems3 Claisen Rearrangement of Multi-Functionalized 2-(Alkenyl)dihydropyran Systems3.1 Synthetic Strategy for Spiro[4.5]decanes3.2 Synthesis of Claisen Substrates and their Rearrangement3.3 Claisen Rearrangement in 2-(Z-Alkenyl)dihydropyran Systems4 Application to the Synthesis of Spirocyclic Sesquiterpenes4.1 Synthesis of Racemic Vetivane Sesquiterpenes4.2 Synthesis of Racemic Gleenol and Axenol4.3 Asymmetric Synthesis of (+)-α-Vetispirene and (–)-Agarospirol4.4 Stereocontrolled Synthesis of (–)-Gleenol4.5 Solvent Effects in the Claisen Rearrangement of 2-(Alkenyl)dihydropyrans4.6 Stereocontrolled Synthesis of the Antimalarial Sesquiterpene, (+)-Axisonitrile-35 Claisen Rearrangement in Pyranoindoles Providing Spirocyclic Oxindoles5.1 Synthetic Strategy for Spirocyclic Oxindoles5.2 One-Pot Intramolecular Ullmann Coupling (IUC)/Claisen Rearrangement6 Application to the Synthesis of Pyrrolidinoindoline Alkaloids; Synthesis of (–)-Flustramine B7 Conclusion PB - © Georg Thieme Verlag DO - 10.1055/s-0031-1290982 UR - http://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0031-1290982 ER -