Novel chiral xylofuranose-based phosphinooxathiane and phosphinooxazinane ligands for palladium-catalyzed asymmetric tandem allylic allylation

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

“…[154] Similar reactions of a-substituted cyclic ketones 44 [161] and 103 [163] with (E)-2-butenyl carbonate (92 g) also afforded linear products: the a,a-disubstituted cyclic ketones 102 and 104 were formed with 90 and 82 % ee, respectively (Scheme 35). Morpholine derivatives 109 a,b can be constructed with 90-94 % ee by the asymmetric intermolecular and subsequent intramolecular allylic substitution of 1,4-diacetoxy-(Z)-2-butene (107) with aminoalcohols 108 a [178] and 108 b [179] as well as L168 and L130, respectively (Scheme 37). [178] This protocol has been applied to the total synthesis of NAS-181.…”

“…Morpholine derivatives 109 a,b can be constructed with 90-94 % ee by the asymmetric intermolecular and subsequent intramolecular allylic substitution of 1,4-diacetoxy-(Z)-2-butene (107) with aminoalcohols 108 a [178] and 108 b [179] as well as L168 and L130, respectively (Scheme 37). [178] This protocol has been applied to the total synthesis of NAS-181. [178] However, the reaction of 2-butene-1,4-biscarbonate in the presence of pyridine-phosphane ligand L67, [180] chiral BHMP-b-Ala L169, [181] (S)-MeO-biphep L170, [182] or (R)-binap ((R)-L117) [183] afforded the related products with low to modest enantioselectivity (44-71.4 % ee).…”

“…[178] This protocol has been applied to the total synthesis of NAS-181. [178] However, the reaction of 2-butene-1,4-biscarbonate in the presence of pyridine-phosphane ligand L67, [180] chiral BHMP-b-Ala L169, [181] (S)-MeO-biphep L170, [182] or (R)-binap ((R)-L117) [183] afforded the related products with low to modest enantioselectivity (44-71.4 % ee).…”

Metallkatalysierte enantioselektive Allylierungen in der asymmetrischen Synthese

“…L130 hergestellt werden (Schema 37). [178] Dieses Verfahren wurde in der Totalsynthese von NAS-181 genutzt. [178] Dagegen wurden bei der Umsetzung von 2-Buten-1,4-dicarbonat in Gegenwart von Liganden wie dem Pyridin-Phosphan L67, [180] dem chiralen BHMP-bAla (L169), [181] (S)-MeO-Biphep (L170) [182] oder (R)-Binap ((R)-L117) [183] nur mäßige Enantioselektivitäten erzielt (44-71.4 % ee).…”

The Development of Bidentate P,N Ligands for Asymmetric Catalysis

“…[46] 3.5 Oxazinane N Donor Related ligands to 116 ± 118 are the oxazinane ligands 121 ± 124 and 125 ± 128 which contain a six-membered ring. [47,48] Ligands 121 ± 124 were also applied in palladium-catalysed allylic alkylation with the standard diphenylallyl substrate 15, Table 8, entries 6 ± 12, and ligands 125 ± 128 were tested in cascade allylic alkylations where ligand 128 afforded a 67% yield and 94% enantiomeric excess of the (S)-product 131, Scheme 8.…”