Burgess water splitting

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Structural formula of the Burgess reagent

The Burgess dehydration is a name reaction in organic chemistry , which was first described in 1970 by Edward M. Burgess (1934-2018) and his colleagues. The reaction is a dehydration of secondary and tertiary alcohols with the help of the Burgess reagent in order to synthesize the corresponding olefins in a targeted manner .

Overview reaction

In the Burgess elimination of water, a secondary or tertiary alcohol is 1 with the Burgess reagent and a syn - elimination to the corresponding alkene 2 implemented.

Overview reaction.svg

The reaction has the advantage over dehydration that it takes place under mild conditions. These include low temperatures and a neutral medium. Thus, almost quantitative yields can be achieved even with acid-sensitive substrates, which are prone to react further. The elimination is syn -selective, although this selectivity is higher with secondary alcohols. Tertiary alcohols, on the other hand, tend to react faster and under milder conditions.

Reaction mechanism

The addition of the Burgess reagent to the alcohol initially leads to the formation of a sulfamate ester in the proposed reaction mechanism . When heated, this reacts in a stereospecific intramolecular syn elimination to form the alkene as a reaction product, with triethylammonium sulfonyl carbamate being formed as a by- product .

Mechanism Burgess water splitting.svg

Atomic economy

In the Burgess dehydration process, triethylammonium sulfonyl carbamate is produced in a stoichiometric amount as waste material, which means that the atomic efficiency can be classified as relatively poor.

modification

The Burgess reagent can also be used with many other functional groups , including epoxides , alkenes , alkynes , aldehydes , ketones , acetals , amides and esters . This enables efficient dehydration of highly functional molecules .

In the second half of the 1980s, the Burgess reagent was also used for the dehydration of primary amides and oximes to form the corresponding nitriles at room temperature . Other compounds can also be dehydrated with the Burgess reagent, such as formamides which give isonitriles , urea which is converted to carbodiimides and primary nitroalkanes which react to nitrile oxides .

Primary alcohols react with the Burgess reagent to form the corresponding carbamates , which in turn react to primary amines through the subsequent hydrolysis.

application

The reaction is used, among other things, to produce antibiotics . For example, the Burgess dehydration also plays a role in the manufacture of the antibiotic herbicidin B. Here a secondary alcohol is first formed, which reacts further with the help of the Burgess reagent, so that an enone is formed. In a final step, this enone reacts further to form herbicidin B.

Individual evidence

  1. ^ A b Edward M. Burgess, Harold R. Penton, Edward Alan Taylor: Synthetic applications of N-carboalkoxysulfamate esters . In: Journal of the American Chemical Society . tape 92 , no. 17 , 1970, pp. 5224-5226 , doi : 10.1021 / ja00720a041 .
  2. ↑ Barbara Czakó: Strategic applications of named reactions in organic synthesis: background and detailed mechanisms . Elsevier Academic Press, Amsterdam 2005, ISBN 0-12-429785-4 , pp. 72-73 .
  3. ↑ a b c Zerong Wang: Irvine-Purdie methylation. In: Comprehensive Organic Name Reactions and Reagents. John Wiley & Sons, Hoboken, NJ, USA 2010, ISBN 978-0-470-63885-9 , pp. 1526-1529, DOI: 10.1002 / 9780470638859.conrr341.
  4. ↑ David A. Claremon, Brian T. Phillips: An efficient chemoselective synthesis of nitriles from primary amides . In: Tetrahedron Letters . tape 29 , no. 18 , 1988, pp. 2155-2158 , doi : 10.1016 / S0040-4039 (00) 86697-6 .
  5. ↑ Mild and Efficient Dehydration of Oximes to Nitriles Mediated by the Burgess Reagent . In: Synlett . tape 2000 , no. 08 , 2000, p. 1169-1171 , doi : 10.1055 / s-2000-6752 .
  6. ^ Siobhan M. Creedon, H. Kevin Crowley, Daniel G. McCarthy: Dehydration of formamides using the Burgess Reagent: a new route to isocyanides . In: Journal of the Chemical Society, Perkin Transactions 1 . No. 6 , 1998, pp. 1015-1018 , doi : 10.1039 / a708081f .
  7. ↑ Mark R. Barvian, HD Hollis Showalter, Annette M. Doherty: Preparation of N, N'-bis (aryl) guanidines from electron deficient cardamines via masked carbodiimide . In: Tetrahedron Letters . tape 38 , no. 39 , 1997, pp. 6799-6802 , doi : 10.1016 / S0040-4039 (97) 01598-0 .
  8. ↑ Nathalie Maugein, Alain Wagner, Charles Mioskowski: New conditions for the generation of nitrile oxides from primary nitroalkanes . In: Tetrahedron Letters . tape 38 , no. 9 , 1997, pp. 1547-1550 , doi : 10.1016 / S0040-4039 (97) 00101-9 .
  9. ^ Edward M. Burgess, Harold R. Penton, E. Alan Taylor, W. Michael Williams: Conversion of Primary Alcohols to Urethanes via the Inner Salt of Methyl (Carboxysulfamoyl) Triethylammonium Hydroxide: Methyl n-Hexylcarbamate . In: Organic Syntheses . No. 56 . American Cancer Society, 1977, ISBN 0-471-26422-9 , pp. 40-43 , doi : 10.1002 / 0471264180.os056.10 .
  10. ^ Francis Tavares, Jon P. Lawson, AI Meyers: Total Synthesis of Streptogramin Antibiotics. ( -) - Madumycin II . In: Journal of the American Chemical Society . tape 118 , no. 13 , 1996, pp. 3303-3304 , doi : 10.1021 / ja954312r .
  11. ↑ a b Satoshi Ichikawa, Satoshi Shuto, Akira Matsuda: The First Synthesis of Herbicidin B. Stereoselective Construction of the Tricyclic Undecose Moiety by a Conformational Restriction Strategy Using Steric Repulsion between Adjacent Bulky Silyl Protecting Groups on a Pyranose Ring † . In: Journal of the American Chemical Society . tape 121 , no. 44 , 1999, pp. 10270-10280 , doi : 10.1021 / ja992608h .