Chiral N-Phosphonyl Imines for an Aza-Morita–Baylis–Hillman Reaction via Group-Assisted Purification (GAP) Chemistry

Abstract

Seventeen examples of aza-Morita-Baylis-Hillman (aza-MBH) adducts have been synthesized by reacting chiral N-phosphonyl imines with acrylonitrile in good to excellent yields (up to 96%) and high diastereoselectivity (up to 99:1 dr). The synthesis of these adducts followed the method of group-assisted purification (GAP) chemistry, in which the pure aza-MBH products were readily obtained by washing the crude products with cosolvents of hexane and ethyl acetate.

Environmentally Friendly Protocol for the Oxidative Iodofunctionalization of Olefins in a Green Solvent

“…This indicated that 1a was converted to 2a in quantitative yield and that the current reaction system did not generate any organic waste. In addition, the present methodology fulfills the key criteria of group-assisted purification chemistry/technology, − in which the products can be isolated conveniently by controlling solubility of desired products, thereby avoiding the chromatography step. A control experiment indicated that I 2 O 5 was essential for successful conversion (entry 13).…”

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

“…[ 45 ] It is noteworthy that the purification of desired product only needs to be carried out by washing with 95% EtOH solvent without traditional chromatography and recrystallization, which followed the group‐assisted purification (GAP) chemistry/technology. [ 46‐48 ] The formation of products 21 and 23 undergoes a very similar pathway including [2 + 2] cycloaddition, 1,6‐nucleophilic addition, ring opening of the cyclobutene and deprotonation/isomerization sequence (Scheme 7b).…”

Asymmetric [4 + 2] cycloaddition synthesis of 4H-chromene derivatives facilitated by group-assisted-purification (GAP) chemistry

“…34 Over the past decade, our group has developed Group-Assisted Purication (GAP) chemistry. [40][41][42][43][44] In essence, highly functionalized chiral N-phosphonyl/N-phosphinyl imines were a Mannich-type reaction, 45 aza-MBH reaction, 46 Strecker reaction, 43 Umpolung reaction, 47 and the synthesis of peptides 48 among others. Recently, our group discovered a novel form of chirality, multi-layer 3D chirality, via GAP chemistry in which restriction of the free rotation of intramolecular layers generates chirality.…”

“…In addition, it provides a benign and facile method to separate the final product after completion of the reaction by simply washing the crude mixture with common solvents such as hexanes to bypass expensive and time-consuming traditional methods such as column chromatography and recrystallization. 40 Many asymmetric reactions were successfully performed via GAP chemistry, including a Mannich-type reaction, 45 aza-MBH reaction, 46 Strecker reaction, 43 Umpolung reaction, 47 and the synthesis of peptides 48 among others. Recently, our group discovered a novel form of chirality, multi-layer 3D chirality, via GAP chemistry in which restriction of the free rotation of intramolecular layers generates chirality.…”