Regio- and Stereoselective Aminopentadienylation of Carbonyl Compounds

Abstract

A simple and robust protocol is detailed for the preparation of enantioenriched α-substituted(1,4-pentadien-3-yl)amine derivatives. The methodology involves the addition of an in-situ formed pentadienyl indium reagent to chiral tertbutylsulfinimines, previously formed in the same pot. The addition takes place with excellent -regio and diastereoselectivity for a wide range of carbonyl compounds, including -unsubstituted aldehydes and methyl alkyl ketones. The catalytic hydrogenation of the sulfinamines obtained provides a convenient access to chiral α-substituted (3-pentyl)amines. The hydroboration-oxidation of the -(1,4-pentadien-3-yl)amine derivatives, followed by a cyclization under Mitsunobu conditions, takes place with an excellent diastereoselectivity governed by the chiral sulfinyl group.

Efforts toward the Total Synthesis of Elisabethin A

“…The synthesis commenced with a large-scale preparation of orthogonally protected hydroquinone 13 from commercially available vanillin (see Experimental Section ). Selective cleavage of the MOM group 16 followed by merging with ( E )-5-bromopenta-1,3-diene 17 under basic conditions gave rise to dienyl-ether 15 in 97% yield ( Scheme 2 ). 18 The following two-step protecting group manipulation produced compound 16 in 90% yield over two steps.…”

tert-Butanesulfinamides as Nitrogen Nucleophiles in Carbon–Nitrogen Bond Forming Reactions

“…Cyclization through transition state model M5 was proposed to be favored because non-bonding interacwere formed in good yields and excellent diastereoselectivity. [57] To account for the observed stereoinduction, the authors proposed a kinetic-based model involving cyclization via two competitive transition levels of stereoinduction. [51] This approach has been very recently used to develop an asymmetric synthesis of quinolizidine 54, which was used for natural product synthesis (Scheme 11).…”

Generation of ϵ,ϵ‐Difluorinated Metal‐Pentadienyl Species through Lanthanide‐Mediated C−F Activation

“…[4] Difluoropentadienyl-metal speciesc ould arise from precursors B or C (Scheme1)t hrough insertion reactions with lowvalent metals or metal complexes. [5] However,o wing to the limited synthetic methods to access such fluorinated substrates, [6] we envisaged the generation of the metalpentadienyl complexes throughs ingle CÀFa ctivation of trifluoromethylated dienes D with zero-valent metals, [7] focusingo nl anthanides.…”