Short,Convenient Preparative Procedures for 7-Isopropylidenenorbornane, 7-Isopropylidenenorbornene,and 7-Isopropylidenenorbornadiene

Short synthetic routes to the title compounds 1,–3, from readily available Diels-Alder adduct 5 of 6,6-dimethylfulvene and acrylonitrile are described.     

7-Chloroquinoline: a versatile intermediate for the synthesis of 7-substituted quinolines

A practical synthesis of 7-mono-substituted quinolines has been achieved. Selective reduction of the inexpensive commercial reagent 4,7-dichloroquinoline affords 7-chloroquinoline, which has been converted into more complex 7-mono-substituted quinolines through a series of Pd-catalyzed cross coupling reactions. These studies include the first examples of Suzuki reactions for the preparation of 7-mono-substituted quinolines as well as the first application of the Sonagashira reaction for the synthesis of 7-substituted quinolines. This strategy has been extended to the preparation of 2,7-di-substituted quinolines.     

7-Substituted 8-aza-7-deazaadenosines for modification of the siRNA major groove

Here we describe the synthesis of new 7-substituted 8-aza-7-deazaadenosine ribonucleoside phosphoramidites and their use in generating major groove-modified duplex RNAs. A 7-ethynyl analog leads to further structural diversification of the RNA via post-automated RNA synthesis azide-alkyne cycloaddition reactions. In addition, we report preliminary studies on the effects of eight different purine 7-position modifications on RNA duplex stability and pairing specificity. Finally, the effect on RNAi activity of this type of modification at eight different positions in an siRNA guide strand has been explored. Analogs were identified with large 7-position substituents that maintain adenosine pairing specificity and are well-tolerated at specific positions in an siRNA guide strand.     

Regioselective syntheses of 7-nitro-7-deazapurine nucleosides and nucleotides for efficient PCR incorporation

Substitution at the C(7) position of purine nucleotides by a potent electron-withdrawing nitro group facilitates the cleavage of glycosidic bonds under alkaline conditions. This property is useful for sequence-specific cleavage of DNA containing these analogues. Here we describe the preparation of 7-deaza-7-NO(2)-dA and 7-deaza-7-NO(2)-dG using two different approaches, starting from 2'-deoxy-adenosine and 6-chloro-7-deaza-guanine, respectively. These modified nucleosides were converted to nucleotide triphosphates, each of which can replace the corresponding, naturally occurring triphosphate to support PCR amplification. [structure: see text]     

Editorial board page for “Analytical Letters”, Volume 7, Number 7

Abstract

This is a scanned image of the original Editorial Board page(s) for this issue.     

New Route for Conversion of Camptothecin to 7‐Ethylcamptothecin and 7‐Propylcamptothecin

In this article, a new route for conversion of camptothecin to 7‐ethylcamptothecin and 7‐propylcamptothecin is described. Compared with previous reports, the reaction time of the new synthetic route was greatly shortened to 30 min, and the products were obtained in high yield.     

Editorial board page for “Synthetic Communications”, Volume 7, Number 7

This is a scanned image of the original Editorial Board page(s) for this issue.     

复合物HNO···H2O2内N-H···O蓝移氢键的理论研究

A theoretical study on the blue-shifted H-bond N-H…O and red-shifted H-bond O-H…O in the complexHNO…H_2O_2 was conducted by employment of both standard and counterpoise-corrected methods to calculate thegeometric structures and vibrational frequencies at the MP2/6-31G(d),MP2/6-31 G(d,p),MP2/6-311 q G(d,p),B3LYP/6-31G(d),B3LYP/6-31 G(d,p) and B3LYP/6-311 G(d,p) levels.In the H-bond N-H…O,the calcu-lated blue shift of N-H stretching frequency is in the vicinity of 120 cm~(-1) and this is indeed the largest theoreticalestimate of a blue shift in the X-H…Y H-bond ever reported in the literature.From the natural bond orbital analy-sis,the red-shifted H-bond O-H…O can be explained on the basis of the dominant role of the hyperconjugation.For the blue-shifted H-bond N-H…O,the hyperconjugation was inhibited due to the existence of significant elec-tron density redistribution effect,and the large blue shift of the N-H stretching frequency was prominently due tothe rehybridization of sp~n N-H hybrid orbital.     

Practical procedure for epimerization of 7α-amino-1-oxacephems to 7β-amino epimers

7α-Amino-1-oxacephems can be epimerized to their 7β-amino epimers by treatment with chloral to give Schiff bases, followed by dehydrochlorination with Hünig base, borohydride reduction, and hydrolysis.     

Duplex Stability of 7-Deazapurine DNA: Oligonucleotides containing 7-bromo- or 7-iodo-7-deazaguanine

The oligonucleotide building blocks, the phosphonates 1a, b and the phosphoramidites 2a, b derived from 7-iodo- and 7-bromo-7-deaza-2′-deoxyguanosines 3a, b were prepared. They were employed in solid-phase oligonucleotide synthesis of the alternating octamers d(Br⁷c⁷G-C)₄ ( 8 ) and d(I⁷c⁷G-C)₄ ( 9 ) as well as the homo-oligonucleotides d[(Br⁷c⁷G)₅-G] ( 11 ) and d[(I⁷c⁷G)₅-G] ( 12 ). The melting profiles and CD spectra of oligonucleotide duplexes were measured. The T_m values as well as the thermodynamic data were determined and correlated to the major-groove modification of this DNA. The self-complementary octamers 8 and 9 form more stable duplexes compared to the parent oligomer d(G-C)₄. The heteroduplex of d[(I⁷c⁷G)₅-G] ( 12 ) with d(C₆) is slightly destabilized (ΔT_m = ?12°) over that of d[(c⁷G)₅-G] with d(C₆). However, the complex of 12 with poly(C) is more stable than that of d[(c⁷G₅-G)] with poly(C).     

合成FOX-7方法的改进

二氨基二硝基乙烯(FOX-7); 甲基咪唑; 合成;合成FOX-7方法的改进     

A new synthetic method for 7α-methoxycephalosporins

A new synthetic route for 7α-methoxy-7β-acylaminocephalosporins is described.     

List of Reviewers for Volume 7 of Cellulose

Other Index

List of Reviewers for Volume 7 of Cellulose