P-azido alcohols

Nucleophilic ring opening of epoxides by ammonia (Section 16 12) The strained ring of an epoxide is opened on nucleo philic attack by ammonia and amines to give 3 ammo alcohols Azide ion also re acts with epoxides the products are p azido alcohols... 

The DKRs of (J-azido alcohols and p-hydroxy nitriles were also accomplished hy employing 1 and CALB with PCPA as the acyl donor. The DKRs of p-azido alcohols were performed at 60°C while those of (3-hydroxy nitriles required higher temperature (100°C) primarily to enhance the racemization rate. The optical purities of products were satisfactory in all cases. In the case of p-hydroxy nitriles, dehydrogenation lowered the yield. 

Cyclization of haloamines 0-46 Cyclization of amino alcohols 0-61 Cyclization of p-azido alcohols 5-31 From 3-iodo azides... 

Pamies, O., and Baeckvall, J.-E. 2001. Dynamic kinetic resolution of P-azido alcohols. An efficient route to chiral aziridines and P-amino alcohols. J. Org. Chem., 66(11), 4022 1025. 

P-Azido alcohols. Opening of epo is catalyzed by BU4NF under solvent-free cc... 

P-Azido alcohols. The epoxide opening by MesSiNs is catalyzed by (t-BuN)2CrCl2. 

P-Azido alcohols. The opening of epoxides by MejSiNj is catalyzed by (salen)Cr(lIl) or Ph SbOH. The products may be hydrolyzed or the silyl ethers isolated. 

Scheme 4.3 Synthesis of p-azido alcohols and p-hydrojg nitriles catalysed by two enzymes.

An efficient DKR of p-azido alcohols was reported in 2001 by Backvall and coworkers. The chiral p-azido alcohol products are useful as direct precursors of aziridines and p-amino alcohols. Shvo s catalyst 1 (4—6 mol%) was used for the racemization and CALB for the kinetic resolution [74]. Good isolated yields (70-87%) of the products were obtained with enantiomeric excesses exceeding 99% in many cases (13). In all cases, small amounts of the corresponding ketones (2-8%) were observed as by-products during the hydrogen transfer process, probably due to the high temperature used (80°C). 

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