Final R indices [I>2sigma(I)] R1 = 0.0592, wR2 = 0.1288 R indices (all data) R1 = 0.0704, wR2 = 0.1406 Largest diff. peak and hole 2.560 and -1.623 e.Е -3 C(5)-H(5A) 0.9900 C(5)-H(5B) 0.9900 C(7)-H(7A) 0.9800 C(7)-H(7B) 0.9800 C(7)-H(7C) 0.9800 C(8)-H(8D) 0.9800 C(8)-H(8A) 0.9800 C(8)-H(8B) 0.9800 O(1)-Sn(1)-O(3) 78.5(2) O(1)-Sn(1)-Cl(1) 88.58(18) O(3)-Sn(1)-Cl(1) 166.79(18) Cl(3)-Cl(4)-Cl(2) 86.56(7) Sn(1)-Cl(4)-Cl(1)#2 128.56(9) Cl(3)-Cl(4)-Cl(1)#2 108.51(8) Cl(2)-Cl(4)-Cl(1)#2 119.29(9) C(1)-O(1)-Sn(1) 127.5(6) C(1)-O(2)-C(7) 116.7(7) C(3)-O(3)-Sn(1) 126.5(6) C(3)-O(4)-C(8) 117.3(7) O(1)-C(1)-O(2) 122.0(9) O(1)-C(1)-C(2) 125.4(9) O(2)-C(1)-C(2) 112.6(8) C(3)-C(2)-C(1) 118.5(8) S9 C(3)-C(2)-C(5) 118.8(8) C(1)-C(2)-C(5) 116.2(8) C(3)-C(2)-C(4) 115.9(8) C(1)-C(2)-C(4) H(8D)-C(8)-H(8A) 109.5 O(4)-C(8)-H(8B) 109.5 H(8D)-C(8)-H(8B) 109.5 H(8A)-C(8)-H(8B) 109.5 _____________________________________________________________ Symmetry transformations used to generate equivalent atoms:4) -169.99(18) O(3)-Sn(1)-Cl(3)-Cl(4) -90.99(19) Cl(1)-Sn(1)-Cl(3)-Cl(4) 101.71(9) Cl(2)-Sn(1)-Cl(3)-Cl(4) -125.4(4) O(1)-Sn(1)-Cl(3)-Cl(1) 88.29(18) O(3)-Sn(1)-Cl(3)-Cl(1) 167.30(19) Cl(4)-Sn(1)-Cl(3)-Cl(1) -101.71(9) Cl(2)-Sn(1)-Cl(3)-Cl(1) 132.8(4) Cl(4)#1-Cl(1)-Cl(3)-Sn(1) 167.34(11) Cl(2)-Cl(1)-Cl(3)-Sn(1) -6.27(6) 1 H NMR (400.1 MHz, CD 2 Cl 2 )

A new type of donor-acceptor cyclopropane reactivity has been discovered. On treatment with anhydrous GaCl3 , they react as sources of even-numbered 1,2- and 1,4-dipoles instead of the classical odd-numbered 1,3-dipoles due to migration of positive charge from the benzyl center. This type of reactivity has been demonstrated for new reactions, namely, cyclodimerizations of donor-acceptor cyclopropanes that occur as [2+2]-, [3+2]-, [4+2]-, [5+2], [4+3]-, and [5+4]-annulations. The [4+2]-annulation of 2-arylcyclopropane-1,1-dicarboxylates to give polysubstituted 2-aryltetralins has been developed in a preparative version that provides exceedingly high regio- and diastereoselectivity and high yields. The strategy for selective hetero-combination of donor-acceptor cyclopropanes was also been developed. The mechanisms of the discovered reactions involving the formation of a comparatively stable 1,2-ylide intermediate have been studied.

The definition of DNA and RNA G-quadruplexes (G4s) has recently been broadened to include structures with certain defects: bulges, G-vacancies or mismatches. Despite the striking progress in computational methods for assessing G4 folding propensity, predicting G4s with defects remains problematic, reflecting the enhanced sequential diversity of these motifs. "Imperfect" G4 motifs, i.e., those containing interrupted or truncated G-runs, are typically omitted from genomic analyses. We report here studies of G4s with defects and compare these structures with classical ("perfect") quadruplexes. Thermal stabilities and ligand interactions are also discussed. We exploited a simple in-house computational tool for mining putative G4s with defects in the human genome. The obtained profiles of the genomic distribution of imperfect G4 motifs were analyzed. Collectively, our findings suggest that, similar to classical G4s, imperfect G4s could be considered as potential regulatory elements, pathology biomarkers and therapeutic targets.