An unprecedented Cu(I)-pybox-diPh-catalyzed highly enantioselective (up to >99% ee) alkynylation/lactamization cascade has been developed as a general catalytic system for the synthesis of diversely substituted isoindolinones of immense biological importance. The cascade effects one C-C and two C-N bond-forming events in one reaction vessel under operationally simple, additive-free reaction conditions in good to excellent yields. The methodology was further extended to the synthesis of tetrahydroisoquinoline scaffolds common to several biologically active natural products in a two-step sequence with remarkable selectivity (up to 94% ee).
We describe herein a highly diastereo‐ and enantioselective [4+3]‐cycloannulation of ortho‐quinone methides and carbonyl ylides to furnish functionalized oxa‐bridged dibenzooxacines with excellent yields and stereoselectivity in a single synthetic step. The combination of rhodium and chiral phosphoric acid catalysis working in concert to generate both transient intermediates in situ provides direct access to complex bicyclic products with two quaternary and one tertiary stereogenic centers. The products may be further functionalized into valuable and enantiomerically highly enriched building blocks.
A highly straightforward route to enantiomerically highly enriched cis-2,3-dihydrobenzofurans has been achieved via addition of α-diazocarbonyl compounds to in situ generated o-QMs catalyzed by a chiral Brønsted acid. This catalytic strategy provides a direct access to 2,3-dihydrobenzofurans in high yields and with up to 91:9 dr and 99:1 er at ambient temperature. Moreover, a unique phenonium-type rearrangement accounts for product formation with an inverted 2,3substitution pattern.
A novel and efficient synthesis of a variety of isoindolinones and tetrahydroisoquinolines via a Lewis acid catalyzed domino Mukaiyama-Mannich lactamization/alkylation is achieved. This transformation comprises a sequential formation of three new bonds through a one-pot, three-component procedure to afford product in moderate to high yields. A concise synthesis of (±)-homolaudanosine (2b) has been achieved using this method.
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