182058-02-2Relevant academic research and scientific papers
Reversible P(III)/P(V) redox: Catalytic aza-Wittig reaction for the synthesis of 4(3H)-quinazolinones and the natural product vasicinone
Wang, Long,Wang, Ying,Chen, Min,Ding, Ming-Wu
, p. 1098 - 1104 (2014/04/03)
The catalytic aza-Wittig reaction based on a phosphine/phosphine oxide catalytic cycle is reported. The by-product triphenylphosphine oxide (Ph 3PO) was reduced in situ to triphenylphosphine (Ph3P) with good chemselectivity so that the aza-Wittig reaction can be accomplished by using merely a catalytic amount of triphenylphosphine. The reaction has been demonstrated in an efficient synthesis of 4(3H)-quinazolinones and the natural product (S)-vasicinone in high yields, by using a catalytic amount of triphenylphosphine (5%) and the tetramethyldisiloxane/titanium tetraisopropoxide [TMDS/Ti(O-i-Pr)4] reductant system (81-95% yields and >99% ee).
Synthesis of optically active vasicinone based on intramolecular aza-Wittig reaction and asymmetric oxidation
Eguchi, Shoji,Suzuki, Toshio,Okawa, Tomohiro,Matsushita, Yuji,Yashima, Eiji,Okamoto, Yoshio
, p. 7316 - 7319 (2007/10/03)
Both optical isomers of a quinazoline alkaloid, vasicinone, were synthesized by two different methods. The first method used (3S)-3-hydroxy-γ-lactam as a chiral synthon, which was, after O-TBDMS protection, o-azidobenzoylated followed by treatment with tri-n-butylphosphine to afford (S)-(-)-vasicinone via the tandem Staudinger/intramolecular aza-Wittig reaction. The second method utilized asymmetric oxygenation of deoxyvasicinone with (1S)-(+)- or (1R)-(-)-(10-camphorsulfonyl)oxaziridine (the Davis reagent), respectively. The aza-enolate anion of deoxyvasicinone was treated with (S)-(+)-reagent to afford (R)-(+)-vasicinone in 71% ee, while the reaction with (R)-(-)-reagent gave (S)-(-)-vasicinone in 62% ee. The optical purity was analyzed by HPLC on specially modified cellulose as a stationary phase. These results provided a facile method to prepare both optical isomers of vasicinone and confirmed the recently reversed stereochemistry of natural (-)-vasicinone.
