TY - JOUR

T1 - A Nazarov‐Ene Tandem Reaction for the Stereoselective Construction of Spiro Compounds

AU - Kalesse, Markus

AU - Etling, Christoph

AU - Tedesco, Giada

N1 - Funding Information: We thank Dr. J. Fohrer, M. Rettstadt and D. K?rtje for detailed NMR analysis and Dr. G. Dr?ger, A. Schulz and R. Reichel for mass spectra. We thank A. Eggert, Y. Linne and L. Millbrodt for assisting in the preparation of the manuscript. C. E. thanks Dr. E. A. Stempel for support in the early stages of the project. Open access funding enabled and organized by Projekt DEAL.

PY - 2021/6/25

Y1 - 2021/6/25

N2 - The different reactivity of trienones under Lewis and Brønsted acids catalysis was investigated, resulting in distinct cyclization products and carbon backbones that originated either from a conjugate Prins cyclization or an interrupted Nazarov cyclization. In particular, an unprecedented Nazarov cyclization tandem reaction is presented, terminating the oxyallyl cation by an ene-type reaction, and leading stereoselectively to bicyclic spiro compounds. The terminal olefin of this motif represents a useful handle for further functionalization, making it a strategic intermediate in total syntheses. The tandem Nazarov/ene cyclization was shown to be preferred over a Nazarov/[3+2] tandem reaction for all our substrates, independent of chain length. Deuteration studies further support the mechanistic hypothesis of the terminating ene reaction.

AB - The different reactivity of trienones under Lewis and Brønsted acids catalysis was investigated, resulting in distinct cyclization products and carbon backbones that originated either from a conjugate Prins cyclization or an interrupted Nazarov cyclization. In particular, an unprecedented Nazarov cyclization tandem reaction is presented, terminating the oxyallyl cation by an ene-type reaction, and leading stereoselectively to bicyclic spiro compounds. The terminal olefin of this motif represents a useful handle for further functionalization, making it a strategic intermediate in total syntheses. The tandem Nazarov/ene cyclization was shown to be preferred over a Nazarov/[3+2] tandem reaction for all our substrates, independent of chain length. Deuteration studies further support the mechanistic hypothesis of the terminating ene reaction.

KW - cyclization

KW - domino reactions

KW - ene reaction

KW - Nazarov cyclization

KW - spiro compounds

UR - http://www.scopus.com/inward/record.url?scp=85106745902&partnerID=8YFLogxK

U2 - 10.1002/chem.202101041

DO - 10.1002/chem.202101041

M3 - Article

VL - 27

SP - 9257

EP - 9262

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 36

ER -