Aza-Darzens Asymmetric Synthesis of <i>N</i>-(<i>p</i>-Toluenesulfinyl)aziridine 2-Carboxylate Esters from Sulfinimines (<i>N</i>-Sulfinyl Imines)
作者:Franklin A. Davis、Hu Liu、Ping Zhou、Tianan Fang、G. Venkat Reddy、Yulian Zhang
DOI:10.1021/jo990907j
日期:1999.10.1
The one-step aza-Darzens reaction of sulfinimines 2 with lithium alpha-bromoenolates readily affords diversely substituted cis and trans N-sulfinylaziridine 2-carboxylate esters 3 and 7 in good yield and excellent diastereoselectivity. Higher yields, but lower de's, result when a mixture of the alpha-bromo ester and 2 are treated with base. The N-sulfinyl group is transformed, nearly quantitatively, without ring opening, into the N-tosyl activating group by oxidation with m-CPBA. Selective removal of the N-sulfinyl group in aziridines 3a and 3h with TFA/H2O affords VI-aziridines 21 which are difficult to prepared by other means. However, C(3) activated azirines such as 3b undergo ring-opening under these conditions. Alternatively, the N-sulfinyl group, even in C(3)-activated aziridines, was selectively and efficiently removed by treatment of the aziridine with 2 equiv of MeMgBr.
Asymmetric Synthesis using Sulfinimines (Thiooxime S-Oxides)
作者:Franklin A. Davis、Padma S. Portonovo、Rajarathnam E. Reddy、G. Venkat Reddy、Ping Zhou
DOI:10.1080/10426509708545525
日期:1997.1.1
Asymmetric synthesis of the antibiotic (+)-thiamphenicol using cis-N-(p-toluenesulfinyl)aziridine 2-carboxylic acids
作者:Franklin A Davis、Ping Zhou
DOI:10.1016/s0040-4039(00)78334-1
日期:1994.10
A concise, highly efficient asymmetric synthesis of aminopropanediol (1R,2R)-(−)-3, precursor to the broad spectrum antibiotics thiamphenicol/florfenicol , was prepared in two steps from cis-aziridine 2-carboxylic acid (2S,3S)-(−)-5.