[reaction: see text] A newly developed strategy for eight-membered oxygen heterocycle construction via [3 + 4] annulation is described. The method involves the combination of beta-substituted acryloylsilanes and enolates of 6-oxacyclohept-2-en-1-one. A unique feature of this annulative approach is its capacity to generate eight-membered ring systems containing useful functionalities for further synthetic elaboration from readily available three- and four-carbon components.

rings with 7 or more members rings with 7 or more members Q 0050 -079Stereoselective Construction of Eight-Membered Carbocycles by Brook Rearrangement-Mediated [3 + 4] Annulation.-An efficient method for the stereocontrolled synthesis of eight-membered carbocyclic compounds bearing various functional groups (V) is presented, involving the Brook rearrangement-mediated [3 + 4] annulation reaction of β-substituted acryloylsilanes (I) with cycloheptenone enolates (II), followed by diastereoselective hydroxylation and oxidative cleavage of the α-hydroxy ketone moiety.

The new approach involves combination of β-substituted acryloylsilanes and enolates of 6-oxacyclohept-2-en-1-one. A unique feature of this annulative approach is its capacity to generate eight-membered ring systems containing useful functionalities for further synthetic elaboration from readily available three-and four-carbon components. -(SAWADA, Y.; SASAKI, M.; TAKEDA*, K.; Org. Lett. 6 (2004Lett. 6 ( ) 13, 2277Lett. 6 ( -2279 Dep. Synth. Org. Chem., Grad. Sch. Med. Sci., Hiroshima Univ., Minami, Hiroshima 734, Japan; Eng.) -Steudel 43-173