A common strategy for the synthesis of a 7-membered-ring system with a Suzuki-Miyaura coupling followed by an acid/base-promoted intramolecular aldol condensation reaction has been developed. The reaction of 2'-bromoacetophenones with 2-formylphenylboronic acids in the presence of Pd(OAc)(2) and CataCXium PIntB L8 efficiently provided biaryl compounds, which were transformed to a wide array of dibenzo[a,c]cyclohepten-5-ones in excellent yields by a sequential treatment with p-TsOH, followed by 10% aq NaOH.

A method for the regioselective asymmetric aldol addition of 2-alkyl allenoates with aldehydes to provide an α- or γ-adduct depending on the aldehyde pair is reported. In most cases, except enals, a mixture of a chiral bromoborane with 2-alkyl allenoates in the presence of iPrNEt can react with aldehydes to provide efficient γ-addition products as single isomers containing axial and central chirality. On the other hand, observations indicate that enals undergo α-addition to yield highly functionalized adducts, including an α-carbon quaternary center in high levels of diastereo- and enantioselectivity.

Useful tetrahydropyran units such as 3 can be prepared with high diastereoselectivity (d.r.>30:1). A key step is the catalytic asymmetric allyl‐transfer reaction from 1 to achiral aldehydes catalyzed by [{(R)‐binol}TiIV{OCH(CF3)2}2] to give 2 (90–97 % ee). A second allyl‐transfer reaction from 2 to a carbonyl compound leads to 3. binol=2,2′‐binaphthol.

Efficient catalytic asymmetric prop-2-ynylation of achiral aldehydes with allenyltributylstannane promoted by a BINOL-Ti IV complex (10 mol%) is achieved with high enantioselectivity by the use of Et 2 BSPr i .