Asymmetric synthesis of 1,3-aminoketals

Chiral N‐Phosphonylimine Chemistry: Asymmetric Synthesis of N‐Phosphonyl β‐Amino Weinreb Amides

“…The absolute configuration of the product was determined by removing the chiral auxiliary from compound 10a followed by treatment with aqueous HCl in methanol as shown in Scheme . The optical rotation value of the deprotected product was proven to be comparable to that of known compound 11 14a…”

“…Among carbonyl derivatives, Weinreb amides have been paid special attention in organic synthesis, because they can be readily converted into ketones 12–15. For example, Weinreb amides have been successfully utilized for the asymmetric synthesis of 1,3‐aminoketals14a and α‐amino ketones 14b. Recently, several methods for the asymmetric synthesis of β‐amino Weinreb amides have been reported,15–17 which include the use of N ‐sulfinyl imine based carbonyl‐type addition and lithium ( S )‐ N ‐benzyl‐ N ‐α‐methylbenzylamide‐based α,β‐conjugate addition reactions.…”

Diastereoselective preparation of cyclic β-aminoketals. Application to the total synthesis of piperidine alkaloids

“…The mixture was stirred at -78°C until TLC showed no starting conjugated ester. Then a saturated NH 4 Cl aqueous solution was added dropwise and the resulting …”

“…The resulting solution was stirred at room temperature until TLC indicated that the reaction had gone to completion. Then the mixture was carefully quenched with a saturated aqueous solution of NH 4 Cl and extracted with dichloromethane. The organic extract was dried, filtered and concentrated in vacuo.…”

“…The mixture was stirred at -78°C until TLC showed no starting ketone. Methanol (5 mL) was added then a saturated NH 4 Cl aqueous solution (5 mL). The mixture was warmed to room temperature before the addition of water (20 mL).…”