Blum aziridine synthesis

Ring opening of oxiranes using azide is followed by Staudinger reduction of the intermediate azido alcohol to give aziridines. 

Regardless of the regioselectivity of the Sn2 reaction of the azide, the ultimate stereochemical outcome for the aziridine is the same. 

Sasson, Y. Shahak, I. Tsaroom, S. Blum, J. J. Org. Chem. 1978, 43, 4271. Jochanan Blum is a professor at The Hebrew University in Jerusalem, Israel. 

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The Blum aziridine synthesis has found widespread utility in the synthetic community. The field of total synthesis has especially benefited from the... 

Somfai and Ahman have applied the Blum aziridine synthesis to the total synthesis of indolizidine 209D (20). ° Epoxide 18 was opened with sodium azide and the primary alcohol protected as the silyl ether. The azide was then treated with triphenylphosphine and heat, resulting in concomitant reduction and cyclization to give intermediate 19. Aziridine 19 was eventually processed to indolizidine 209D (20). 

Finally, Tanner and Somfai completed a formal total synthesis of thienamycin (26) using the Blum aziridine synthesis as a key step. As in the previous examples, epoxide 24 was converted to aziridine 25 in good yield using a Blum aziridine synthesis. Intermediate 25 was eventually processed to thienamycin (26). 

Robinson and co-workers reported the preparation of aromatase inhibitors that used the Blum aziridine synthesis as a key step. Epoxy-steroid 27 was opened with sodium azide to form the azido-alcohol, which was then reductively cyclized with triphenylphosphine and heat to provide the desired aziridine 28. Analog 28 exhibited modest inhibitory activity toward human placental aromatase. 

Researchers at Lexicon Pharmaceuticals found that limonene aziridines could be efficiently prepared from the corresponding limonene oxides using the Blum aziridine synthesis. Epoxide 32 was opened with sodium azide to produce the regioisomeric azido-alcohols 33 and 34 in an approximate 1 1 ratio. The secondary azide was reductively cyclized with triphenylphosphine at ambient temperature, whereas the tertiary azide required heating to effect the same transformation. In this way, the desired aziridines 35 and 36 were prepared in good yield on multigram scale. 

The Blum aziridine synthesis has seen many other uses since its development. A common application of the Blum aziridine synthesis is in the preparation of authentic standards while developing novel reactions or... 

Blum aziridine synthesis to prepare a chlorodysinosin A intermediate 16 ... 

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