化学经纬
化学经纬

碱性条件下脱除亚磺酰胺

chem化学亮点4.2W+

碱性条件下脱除亚磺酰胺 第1张

我们合成手性的胺可以通过Ellman试剂首先合成亚磺酰胺在酸性条件下脱出亚磺酰胺就可以得到手性胺。如果我们底物含有对酸敏感的基团的时候,酸性脱出亚磺酰胺就会有意想不到的副产物产生。最近有篇文献报道在碱性条件下脱出亚磺酰胺就可以避免有酸性基团的影响。

碱性条件下脱除亚磺酰胺 第2张

In summary, we have developed an iodine mediated single electron transfer process for the deprotection of tertbutanesulfinyl and p-toluenesulfinyl units. For most substrates used in this research, the yields are good to excellent using only catalytic amounts of iodine. Our new methods are especially useful for the deprotection of N-tert-butanesulfinyl amines with acid sensitive structure motifs and should find more applications in the synthesis of complex natural products.


Method A: (For acid sensitive substrates) To a solution of sulfinyl amines (0.5 mmol) in  THF/H2O  (1:1,  10  mL)  was  added  Na2CO3(1.5  mmol,  3.0  eq.)  and  DMAP  (0.1  mmol, 0.2 eq.). The reaction mixture was stirred for 5 min at 20 °C before addition of I2 (1.25  mmol,  2.5  eq.)  under  an  argon  atmosphere.  The  resulting  mixture  was  then stirred at 20 °C under argon for 16-24 h. After consumption of starting materials, the reaction  was  quenched  by  water  (5  mL)  and aqueous  sodium  thiosulphate  (2N,  0.1  mL) at room temperature. The mixture was extracted with CH2Cl2(3 × 5 mL), and the combined  organic  phases  were  dried  (Na2SO4),  and  concentrated.The  residue  was  chromatographed on basic aluminium oxide (petroleum ether 60-90 °C : ethyl acetate : Et3N= 3 : 1 : 0.02 or ethyl acetate : Et3N= 1 : 0.01) to afford the product.

Method B: (Other substrates less labile to acids)To a solution of sulfinyl amines (0.5 mmol) in THF/H2O (5:1, 10 mL) was added iodine (0.1 mmol, 0.2 eq.). The reaction mixture  was  then  stirred  at  50  °C  under  air  or  under  nitrogen  until  completely consumption   of   sulfinyl   amines.   The  reaction   mixture   was   cooled   to   room   temperature and diluted with water (15-20 mL). After removal of THF under reduced pressure, an aqueous solution of sodium thiosulphate (0.2 N, 0.2 mL) was added. The resulting mixture was then washed with Et2O (3 × 5 mL), and the aqueous phase was treated  with  saturated  aqueous  solution  of  NaHCO3  (5  ml).  The  resulting  aqueous  mixture was then extracted with CH2Cl2(3 × 5 mL) and the combined organic phases were  washed  with  brine  and  dried  over  Na2SO4.  After  filtration,  the  solvent  was removed  under  reduced  pressure  to  afford  the  amines.  Chromatography  on  basic  aluminium oxide might be required for some amines.

Ref:Chem. Commun., 2014,50, 6259-6262

发布评论0条评论)

您需要 登录账户 后才能发表评论

还木有评论哦,快来抢沙发吧~