Asymmetric [2,3]Wittig sigmatropic rearrangement involving a chiral azaenolate as the migrating terminus. A simple synthesis of (+)-verrucarinolactone

1,2-Amino Alcohols and Their Heterocyclic Derivatives as Chiral Auxiliaries in Asymmetric Synthesis

“…As an oxazoline can stabilize a carbanion and also contain stereogenic centers, it is a useful moiety for a number of reactions, including the [2,3] Wittig rearrangement. [796][797][798][799][800][801][802][803] The Wittig rearrangement has a number of variables that can determine its outcome. 5 Oxazolines have been used to stabilize the intermediate carbanion.…”

“…The addition of 18-crown-6, however, reverted the product to the R-configuration (Scheme 185). 796,797,804…”

“…As an oxazoline can stabilize a carbanion and also contain stereogenic centers, it is a useful moiety for a number of reactions, including the [2,3] Wittig rearrangement. − …”

“…With the alcohol ( 155 , R = OH) and a potassium counterion, the stereochemical outcome was reversed to provide the S -product. The addition of 18-crown-6, however, reverted the product to the R -configuration (Scheme ). ,,

185

…”

Multi-gram-scale synthesis of a versatile syn-anti stereotriad by a short and cost-effective route

“…26 Our synthetic intermediate syn diad (8) was easily isolated after a [2,3]-Wittig rearrangement of 7. [27][28][29][30][31][32][33] Optimum conditions for this rearrangement required the use of excess t-BuLi (Table 2). This protocol afforded the rearranged 8 without side products.…”