Triple Role of Phenylselenonyl Group Enabled a One-Pot Synthesis of 1,3-Oxazinan-2-ones From α-Isocyanoacetates, Phenyl Vinyl Selenones, and Water

Abstract

Reaction of α-substituted α-isocyanoacetates with phenyl vinyl selenones in the presence of a catalytic amount of base (DBU or Et3N, 0.05-0.1 equiv) followed by addition of p-toluenesulfonic acid (PTSA, 0.1-0.2 equiv) afforded 4,4,5-trisubstituted 1,3-oxazinan-2-ones in good to excellent yields. Enantiomerically enriched heterocycles can also be prepared using a Cinchona alkaloid-derived bifunctional organocatalyst for the Michael addition step. The phenylselenonyl group served as an activator for the Michael addition, a leaving group and a latent oxidant in this integrated reaction sequence.

Synthesis of Oxazolidin‐2‐ones by Oxidative Coupling of Isonitriles, Phenyl Vinyl Selenone, and Water

“…The heteroannulation worked equally well under strictly inert atmosphere, indicating that oxygen is not responsible for the oxidation. The reaction of N ‐butylformamide 7 with 5 under our standard conditions failed to produce even a trace amount of oxazolidinone 6 h , indicating a significant mechanistic deviation from our previous oxazinanone synthesis (Scheme a) . Heating a solution of isocyanate 8 and 5 under standard conditions afforded only a trace amount of oxazolidinone.…”

“…One C−N, two C−O, and one C=O bonds were created in this unprecedented transformation with the isocyano group acting formally as a polarized double bond ( A ) and phenyl vinyl selenone as a latent 1,3‐dipole ( B ) . The phenylselenonyl group served as an electron‐withdrawing group to activate the 1,4‐addition, a leaving group, and a latent oxidant in this transformation …”

“…[11] The phenylselenonyl group served as an electron-withdrawing group to activate the 1,4-addition,aleaving group,a nd al atento xidant in this transformation. [12] The reaction between benzyl isonitrile (4a)a nd phenylv inyl selenone (5)was initially investigated.Inthe presenceofacatalytic amount of cesium hydroxide monohydrate, the reaction between 4a and 5 in tert-butanol at room temperature afforded unexpectedly oxazolidinone 6a in about 20 %y ield (Table 1, entry 1). Realizing the synthetic potential of this transformation, the reaction conditions were systematicallys urveyed.…”

“…The reaction of N-butylformamide 7 with 5 under our standard conditions failed to produce even at race amount of oxazolidinone 6h,i ndicating as ignificant mechanistic deviation from our previous oxazinanone synthesis (Scheme 3a). [12] Heating as olution of isocyanate 8 and 5 under standard conditions afforded only at race amount of oxazolidinone. However,s low addition (5 h) of an excesso fi socyanate 8 (10.0 equiv) to aC H 2 Cl 2 solution of 5 in the presence of Cs 2 CO 3 (0.1 equiv) afforded 6h in 60 %y ield, indicating that isocyanate could be an intermediate in the reaction between isocyanide 4 and phenyl vinyl selenone (5; Scheme 3b).…”

Atom-Economic Synthesis of 4-Pyrones from Diynones and Water

“…Recently, there are many reports of clean transformations in water medium [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], such as coupling reactions [20][21][22][23][24][25][26][27][28][29][30], cyclizations [31][32][33][34], Michael additions [35][36][37][38][39], and condensations [40,41]. Additionally, H2O also participates in organic reactions as a nucleophile [42,43] to provide various kinds of functional compounds such as imidazo [1,2-a]pyridines [44], amino acid salts [45], α-amino ketones [46], and 1,3-oxazinan-2-ones [47]. Thus, the studies of organic reactions in aqueous solvents or H2O-participating reactions are attractive in synthetic chemistry.…”