J . Org. Chem. 1995,60, 3358-3364
3358
Synthesis of Oligonucleotides Containing 3-Alkyl Carboxylic Acids Using Universal, Photolabile Solid Phase Synthesis supports+ Dong J i n
Yo0 and Marc M. G r e e n b e r e
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 Receiued January 31, 1996
The synthesis and application of photolabile supports for solid phase oligonucleotide syntheses t h a t release oligonucleotides containing 3'-alkyl carboxylic acids is described. The carboxylic acid functionality is revealed without removing any other protecting groups throughout t h e biopolymer, and the protected oligonucleotides are amenable to reverse phase HPLC. The solid phase synthesis supports do not contain a nucleoside, making i t possible to use a single support for the synthesis of oligonucleotides independent of their sequence. Individual solid phase synthesis supports differ according to the length of the alkyl tether between t h e 4,4'-dimethoxytrityl group which serves a s t h e initiation site for oligonucleotide synthesis and the latent carboxylic acid. Eicosameric oligonucleotides are obtained in a s high a s 92% yield, under photolysis conditions t h a t are known to produce less than 1%thymidine-thymidine photodimers. Covalent attachment of oligonucleotides to solid supports andlor other molecules in solution is finding a n increasingly larger array of applications.' A number of methodologies for modifying oligonucleotides a t t h e 5'terminus exist. Furthermore, cleverly designed phosphoramidites enable one to functionalize specific sites throughout the biopolymer and even the 3'-terminus.2 Development of the methodology for functionalization of the 3'-terminus of oligonucleotides has generally lagged behind t h a t of chemistries which facilitate conjugation a t other sites within these biopolymers. Recently, we and others have reported on a series of modified solid phase synthesis supports t h a t enable one to synthesize oligonucleotides containing functional groups a t t h e 3'terminus t h a t are amenable to carrying out oligonucleotide conjugation chemistry."," The supports previously described by us have a n additional advantage. Since oligonucleotides synthesized on them are cleaved photolytically, a t room temperature and neutral pH, the biopolymers can be released into solution without affecting the phosphodiester and nucleobase protecting groups. It has been suggested t h a t the synthesis of protected oligonucleotides containing a single reactive moiety a t either terminus will facilitate improvements in oligonucleotide conjugation chemistry.5 We report on the first examples of orthogonal, universal oligonucleotide synthesis supports t h a t enable one to efficiently synthesize
' Presented, in part. at the 208th ACS National Meeting, Washington. DC. August 21-25. 1994. :"Abstract published in Advance ACS Abatmelr. May 15, 1995. l1ilalGoodehild.J. RiocortjugdeChem. 1990.1,165.ibIBeaucage. S. L.: Iver. R. P.Tefmhvdmn 1993. 49. 1925. le1 de la Torrc. R. G.: Anno. A.;Tarrason, G.: Piulats. J.; F.;Eritja. R. Tefrihedmn &If. 1994, 3 5 . 2733. Id) Leonetti, J.-P.; Degols, G.: Lebleu, R. Biwonjwale Chem. 1990 I , 149. l e i Letsinger. R. L.:Zhang. G.; Sun, D.K.: Ikruchi. T.:Sarin. P.S.I'm. Noll. Acod. Sci. U.S.A. 1989.86. 6.553. I f 1 Lurid, V.: Sehmid. R.: Rickwmd. D.; Homes, E. N u e / e ~ r A > i d ~ Rcs. 19RR. 16. 10Rfil. lgi Ghosh. S.S.; Musso, G. F. NueleicAc.id.v Res. 19R7, li.5353. 12) Iiil Nelson. P. 5.;Kent. M.: Muthini. S. Nucleic Acids Res. 1992. 20. 6 2 % Ihl Theisen. P.:MeCollum. C.: Uoadhva. K.: Jambson.. K.:. Vu, H.: Andrus. A. Telrahedmn Leu. 1992.'33. 5033. 131 (a) Greenberg. M. M.: Gilmore. J. L. J . OT#. Chem. 1994.59, 74fi. tbl G r e e n k r,..~ .M. M. Telrahedron 199.5. S I . 29. (4) la) Horinen. J.; Guzaev. A,; Azhayev. A.; Lonnberg, H. Tetmhe. d m n 1994. 5 0 . 7203. Ibl Gottikh. M.; Asseline. U.: Thuong, N. T. Telmhudron I.41. 1990.31. fifi57. i d Gupta. K. C.; Shama, P.:Kumar, P.: Sathyanarayana, S. Nurlr,ic Acids Res. 1991. 19. 3019. ( S i Miller. P. S.; Thaden. J. Riomnjugole
