06-23-04 09:33
No 514991
In route to working to reduce COOH to OH on the amino acid Phenylalanine the need to protect the amine group is necessary unless one is using the NaBO4(+ Iodine, H2SO4). As an alternative method to Boc- , Fmoc-, expensive routes, acetic acid** seems the logical route. Although I'm not sure if I first need to convert the COOH to an ester, to avoid reaction with the COOH group, by refluxing in methanol with some HCL . After acylating the amine the ester has to be removed in order to do the reaction that will work only on the COOOH group........and that's the use of DMT_MM *, which by hydrogenation with Pd will give the acN-amino alcohol.
Hence , will this work in reaching my goal , and how will I remove the acetyl group or maybe do a swap for a methyl group in route to removing it?
Ref.
*Post 430441 (Lego: "Reduction of carboxylic acids to aldehydes", Novel Discourse)
**Post 511768 (demorol: "Protection & Deprotection of various funct. groups", Methods Discourse)
Greetings , from Latin America
.........java
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(Hive Bee)
06-23-04 17:10
No 515066
i was thinking of 1)making the ethyl ester of phenylalanine 2)reducing the ester to form an ether 3)hydroylising the ether 4)reducing the the alcohol to a hydrocarbon. doesn't sodium in alcohol reduce esters to ethers? then sodium in an amine reduces the alcohol. everybody is using sodium in ammonia to reduce the alcohol group in ephedrine and no one ever worries about protecting the nitrogen there. or maybe you could check my post on the protonation of glycine and be the first person to attempt to methylate beta-protonated phenylalanine then decarboxylating the product.
(Hive Bee)
06-29-04 21:03
No 516488
(Rated as: excellent)
This reference was cited by Assholium...Post 434591 (Assholium: "гутрон? оксилидин!", Russian HyperLab)
Removal of Acyl Protecting Groups Using Solid NaOH and a Phase Transfer Catalyst
Synlett 7,991-92,2003
Abstract
Acetyl-, benzoyl- and pivoyl-protected alcohols and phenols undergo smooth deacylation in a two-phase system of powdered NaOH and Bu4NHSO4 in THF or CH2Cl2.
Summary
We have devised a new method for the removal of acetyl-, benzoyl- and some pivoyl-protecting groups from acyl protected alcohols utilizing a two-phase system with tetrabutylammonium hydrogen sulfate as phase transfer catalyst. Furthermore, based on our previous work,(15)this method does not affect alkyl silyl ethers but does deprotect aryl silyl ethers.
References
(1) Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 3rd ed.; Wiley: New York, 1999.
(2) Kocienski, P. J. Protecting Groups; Georg Thieme Verlag: Stuttgart, 1994.
(3)
(a) Jarowicki, K.; Kocienski, P. J. J. Chem. Soc., Perkin Trans 1 2001, 2109.
(b) Jarowicki, K.; Kocienski, P. J. J. Chem. Soc., Perkin Trans 1 2000, 2495.
(4) Ogilvie, K. K.; Iwacha, D. J. Tetrahedron Lett. 1973, 317.
(5) van Boeckel, C. A. A.; van Boom, J. H. Tetrahedron Lett. 1979, 20, 3561.
(6) Nakano, Y.; Ito, Y.; Ogawa, T. Carbohydrate Res. 1993, 243, 43.
(7) Gassman, P. G.; Shenk, W. N. J. Org. Chem. 1977, 42, 918.
(8) Nicolaou, K. C.; Caulfield, T. J.; Kataoka, H.; Stylianides, N. A. J. Am. Chem. Soc. 1990, 112, 3693.
(9) Zheng, Q. Y.; Darbie, L. G.; Cheng, X.; Murray, C. K. Tetrahedron Lett. 1995, 36, 2001.
(10) Xu, Y.-C.; Bizuneh, A.; Walker, C. J. J. Org. Chem. 1996, 61, 9086.
(11) Xu, Y.-C.; Bizuneh, A.; Walker, C. J. Tetrahedron Lett. 1996, 37, 455.
(12) Reinhard, B.; Faillard, H. Liebigs Ann. Chem. 1994, 193.
(13) Rabinovitz, M.; Cohen, Y.; Halpern, M. Angew. Chem., Int. Ed. Engl. 1986, 25, 960.
(14) Illi, V. O. Tetrahedron Lett. 1979, 20, 2431.
(15) Crouch, R. D.; Stieff, M.; Frie, J. L.; Cadwallader, A. B.; Bevis, D. C. Tetrahedron Lett. 1999, 40, 3133.
Comments by Java Although this method was for phenols and alcohols , I wonder if it will work for amine acylated phenylalanine as a method of removal of the acyl group.
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