Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2004 The theoretical approach was to use the B3LYP method and the 6-31g** basis set. However, the '6-31g**' basis for tin was of one of our own. It is one that we used in a previous tin study: Journal of Organic Chemistry (1999), 64(13), 4680-4684. The details can be found there. Generally structures were first found with the b3lyp/sdd method and then reoptimized with the b3lyp/6-31g** method. The exception was the methylated transition state linking 5 and 6 which was determined by substitution of the unmethylated transition state. Structures 5, 6 and 7 arose by optimizing from a transition state. By starting at the transition state and optimizing to find the reactant and product, one hopes to make sure the conformation of each stationary point is consistent with the other two in the reaction sequence. In the case of 5 and 6 they were the reactant and product to the transition state linking them (i.e. the transition state was located before the minima, although a minimum like 5 was located to provide a guess at what the transition state might look like). 7 arose as the product of the Diels-Alder reaction of furan and the tetra-substituted double bond Energy difference 5a/6a = 14.09 kJ mol-1 Energy difference 5b/6b = -11.71 kJ mol-1 The coordinates of structure 5a Energy = -8922.79463432 au (PCM: -8922.810091 au) 6 1.063418 3.055660 -0.953227 6 0.205912 2.411306 0.122564 6 1.206059 1.681426 1.072968 6 1.610459 0.421878 0.209986 6 0.906149 0.779880 -1.146651 6 1.513944 2.050940 -1.708984 8 3.014844 0.353854 0.174481 6 3.541819 -0.658799 -0.604763 8 2.827540 -1.422723 -1.235732 6 0.969336 -0.835507 0.828223 8 -0.204450 -1.171266 0.673197 8 -0.349350 1.278758 -0.600359 50 -2.259531 -0.320340 -0.199170 17 -2.345046 0.858935 1.889406 9 0.648894 1.309659 2.252833 9 2.275540 2.457552 1.373586 17 -1.409068 -1.312418 -2.218722 17 -3.771658 1.147963 -1.313244 17 -3.431372 -2.247275 0.548992 7 4.894738 -0.662878 -0.566725 6 5.611880 -1.680898 -1.324580 6 5.701422 0.263764 0.219881 8 1.796057 -1.508435 1.593782 6 1.265116 -2.702737 2.227360 1 2.086832 -3.091403 2.825404 1 0.409732 -2.440620 2.851368 1 0.960942 -3.417613 1.461554 1 6.199420 -2.314427 -0.649431 1 4.892524 -2.295622 -1.862471 1 6.295385 -1.208617 -2.039569 1 6.271206 -0.282139 0.981691 1 6.412638 0.783016 -0.433076 1 5.066320 0.997492 0.709223 1 1.298929 4.109762 -1.009034 1 2.199328 2.085000 -2.545100 1 0.740501 -0.058274 -1.812889 1 -0.572241 2.981000 0.624158 The coordinates of methylated structure 5b Energy = -8962.11264039 au (PCM: -8962.121913 au) 6 2.122743 -2.994923 1.371438 6 1.785202 -3.802436 0.365855 6 0.659070 -3.080582 -0.355715 6 1.303317 -1.898530 -1.117970 6 1.716761 -0.924783 0.064705 6 1.183394 -1.782668 1.302775 8 0.009676 -2.358791 0.690082 50 -2.525525 1.448615 0.188339 17 -2.120210 1.033169 -2.095749 9 0.390589 -1.302696 -1.940541 9 2.356803 -2.259239 -1.892133 8 3.128112 -0.796269 0.001663 6 3.721881 0.135129 0.814672 7 5.063836 0.181297 0.612339 6 5.775534 -0.621695 -0.374715 6 1.010034 0.424770 -0.151598 8 1.725450 1.212161 -0.934274 6 1.232951 2.546569 -1.192697 6 0.859265 -1.111160 2.618052 8 3.092769 0.816100 1.611991 8 -0.097802 0.692856 0.294279 17 -2.779083 -0.392075 1.610501 17 -1.549519 3.369340 1.144047 17 -4.773031 2.195565 0.040130 6 5.861255 1.101449 1.410587 1 2.043120 3.049891 -1.717956 1 0.342616 2.499178 -1.820932 1 1.007805 3.048717 -0.251289 1 6.370885 1.825427 0.763167 1 5.206123 1.631810 2.099218 1 6.621572 0.552777 1.979634 1 6.327093 0.033668 -1.059601 1 6.497521 -1.282930 0.120689 1 5.074606 -1.223255 -0.947558 1 2.249532 -4.726156 0.046377 1 2.930319 -3.101987 2.084575 1 -0.048494 -3.654946 -0.952780 1 1.760595 -0.676939 3.052412 1 0.120093 -0.323370 2.487243 1 0.452877 -1.865258 3.297982 The coordinates of structure 6a Energy = -8922.77702195 au (PCM: -8922.804728 au) 6 0.451563 -2.099739 0.707510 6 -0.021366 -1.630521 -0.655903 6 1.225087 -1.223635 -1.451521 6 1.801106 0.062611 -0.795330 6 1.767651 -0.024221 0.769181 6 1.307555 -1.319237 1.368644 8 3.255889 0.099253 -1.090277 6 3.917410 0.184482 0.032182 8 3.213592 0.164620 1.123610 6 1.277199 1.412943 -1.354244 8 0.691502 1.570464 -2.389230 8 -0.731079 -0.420759 -0.534731 50 -2.488767 -0.142111 0.483961 17 -3.140395 -2.424271 -0.130573 9 0.966046 -1.043774 -2.761209 9 2.195938 -2.195937 -1.375199 17 -1.457210 2.049224 1.007179 17 -2.671975 -0.639208 2.822224 17 -4.338894 0.861209 -0.617775 7 5.229037 0.286863 0.045510 6 5.973097 0.364609 1.308763 6 6.006788 0.318497 -1.200266 8 1.691982 2.390715 -0.529758 6 1.215341 3.718269 -0.860140 1 1.695106 4.383319 -0.143467 1 1.494744 3.973324 -1.883994 1 0.130676 3.742796 -0.744925 1 6.535949 1.301671 1.337739 1 5.285333 0.327908 2.150557 1 6.669923 -0.476030 1.368519 1 6.581331 1.247967 -1.240564 1 6.694248 -0.531669 -1.216995 1 5.341760 0.263524 -2.059101 1 0.041608 -3.004529 1.143143 1 1.636273 -1.520823 2.383688 1 1.252682 0.839261 1.193113 1 -0.567832 -2.410160 -1.195952 The coordinates of methylated structure 6b Energy = -8962.09314275 au (PCM: -8962.126373 au) 6 0.030333 0.189189 -0.038405 6 0.146457 -0.161139 1.242414 6 1.518084 -0.140049 1.886948 6 2.165179 1.192309 1.495503 6 2.398027 1.258578 -0.051085 6 1.225428 0.569604 -0.869818 8 2.260350 -1.174267 1.310774 50 3.565239 -2.521659 2.163365 17 5.922730 -2.332364 2.500675 9 3.326982 1.417814 2.147376 9 1.325086 2.230964 1.825932 8 2.284214 2.678087 -0.423124 6 1.384144 2.819904 -1.357017 7 1.129734 4.002723 -1.876291 6 1.858142 5.202057 -1.441950 6 3.824151 0.833025 -0.491726 8 4.084153 1.338274 -1.715560 6 5.375658 0.958282 -2.253634 6 1.629301 -0.541306 -1.825983 8 0.769231 1.744601 -1.736427 8 4.583068 0.161712 0.148243 17 3.102252 -1.549049 4.374599 17 3.869153 -3.186390 -0.188045 17 2.581572 -4.619249 2.750206 6 0.099719 4.174579 -2.907118 1 5.410559 1.390293 -3.252807 1 6.173356 1.360032 -1.626005 1 5.459950 -0.129357 -2.288805 1 0.560976 4.565239 -3.818506 1 -0.376828 3.220527 -3.121151 1 -0.650446 4.886040 -2.550771 1 2.351263 5.654706 -2.306567 1 1.151276 5.918115 -1.013706 1 2.603013 4.937789 -0.695046 1 -0.707931 -0.522315 1.805803 1 -0.905542 0.117450 -0.585882 1 1.467913 -0.178422 2.980732 1 0.738387 -0.929547 -2.325516 1 2.336359 -0.184587 -2.576410 1 2.083429 -1.349891 -1.243632 The coordinates of structure 7a Energy = -8922.79658882 au (PCM: -8922.817988 au) 6 -4.245263 -0.594484 0.727877 6 -4.792502 0.700176 0.145800 6 -4.279685 0.776093 -1.085477 6 -3.422650 -0.473982 -1.244602 8 -4.101768 -1.425634 -0.428671 6 -2.742847 -0.353432 1.062318 9 -2.553411 0.792383 1.770350 6 -2.098024 -0.251998 -0.383073 6 -1.062452 -1.338871 -0.704801 8 -1.567040 -2.548415 -0.665544 6 -0.645541 -3.646797 -0.922450 8 -1.604288 1.047918 -0.679033 6 -0.631020 1.618788 0.078442 7 -0.588078 2.945820 -0.021532 6 -1.461528 3.703081 -0.916916 8 0.092043 -1.102002 -1.046028 50 1.988567 -0.175762 0.108007 17 3.407223 -1.738905 -1.012282 9 -2.233419 -1.376649 1.780924 8 0.130941 0.941824 0.804848 6 0.520611 3.683739 0.592697 17 1.273960 -1.734848 1.805488 17 3.418230 1.151568 1.484790 17 1.911753 1.369024 -1.768680 1 -1.258544 -4.542788 -0.851596 1 -0.210714 -3.539480 -1.917118 1 0.140625 -3.638360 -0.166827 1 0.116028 4.563232 1.100849 1 1.034189 3.048201 1.310270 1 1.231232 3.995613 -0.178450 1 -1.634245 4.688456 -0.478361 1 -0.988639 3.827690 -1.897608 1 -2.414392 3.193112 -1.036288 1 -5.400747 1.420976 0.675724 1 -4.370778 1.569312 -1.815344 1 -3.248166 -0.860003 -2.247389 1 -4.794377 -1.097256 1.522489 The coordinates of methylated structure 7b Energy = -8962.12029839 au (PCM: -8962.137912 au) 6 4.189359 0.654267 0.963740 6 3.378035 -0.640765 0.866601 8 4.038758 -1.325030 -0.205641 6 4.110767 -0.229959 -1.122167 6 4.658692 0.896510 -0.261587 6 3.264227 -1.479489 2.118481 6 2.593419 0.056629 -1.324485 9 2.356762 1.348343 -1.686230 6 2.009284 -0.247040 0.116133 8 1.501802 0.915417 0.760955 6 0.478544 1.629768 0.226487 8 -0.330871 1.128355 -0.587412 50 -2.107923 -0.176607 -0.030904 17 -1.564532 -1.211850 -2.145102 9 2.065325 -0.737161 -2.280944 6 1.002573 -1.404277 0.157854 8 -0.111503 -1.315641 0.666896 8 1.486193 -2.522454 -0.327007 6 0.591195 -3.671868 -0.348381 7 0.434555 2.893611 0.642268 6 -0.723929 3.728391 0.308198 6 1.375951 3.438569 1.619289 17 -3.675871 1.415627 -0.876045 17 -1.866341 0.846652 2.162905 17 -3.397025 -2.020973 0.772800 1 1.197601 -4.484298 -0.743300 1 0.243647 -3.889192 0.662549 1 -0.256380 -3.452642 -0.998117 1 -0.366895 4.712050 -0.008568 1 -1.292004 3.267088 -0.496173 1 -1.370319 3.834238 1.184677 1 1.493664 4.506884 1.424950 1 0.994651 3.302053 2.637582 1 2.342642 2.949617 1.524861 1 5.228067 1.744176 -0.619281 1 4.290985 1.247549 1.863302 1 4.629539 -0.503230 -2.039843 1 2.825121 -2.454917 1.902188 1 4.259653 -1.638520 2.540598 1 2.646433 -0.966872 2.861487 The coordinates of the transition state linking 5a and 6a Energy = -8922.75587894 au (PCM: -8922.779722 au) 6 -0.048860 0.331953 0.320784 6 0.017339 0.248666 1.652180 6 1.451812 0.039790 2.104479 6 2.209467 1.332694 1.737159 6 2.350340 1.266419 0.164730 6 1.274344 0.280157 -0.371682 8 1.945631 -0.902708 1.176477 50 3.534570 -2.348264 1.201725 17 5.744735 -3.134024 0.712486 9 3.436301 1.429396 2.299999 9 1.525814 2.452827 2.102497 8 2.074900 2.583404 -0.343020 6 1.333105 2.537391 -1.453721 7 1.149873 3.684209 -2.102901 6 1.772537 4.940891 -1.682365 6 3.784539 0.855813 -0.257503 8 4.323722 1.725654 -1.101734 6 5.661907 1.391661 -1.559813 1 1.552799 -0.522109 -1.044548 8 0.848083 1.428757 -1.802283 8 4.358667 -0.144109 0.124953 17 4.197632 -1.439219 3.349319 17 2.846965 -2.608012 -1.146847 17 2.294434 -4.206522 2.036710 6 0.294232 3.723768 -3.289459 1 5.929800 2.186381 -2.253673 1 6.345409 1.362346 -0.709932 1 5.652924 0.418295 -2.052386 1 0.879313 4.046744 -4.156276 1 -0.114017 2.732924 -3.477890 1 -0.523967 4.433091 -3.129637 1 2.338505 5.360703 -2.519609 1 1.000061 5.656719 -1.383279 1 2.444256 4.765538 -0.845785 1 -0.830516 0.295017 2.324804 1 -0.949717 0.429841 -0.271666 1 1.599833 -0.237699 3.149438 The coordinates of the transition state linking methylated 5b and methylated 6b Energy = -8962.06727965 au (PCM: -8962.085816 au) 6 0.876072 -2.595634 1.225915 6 0.177335 -1.975355 0.039013 6 1.269164 -1.282966 -0.799103 6 1.641939 0.014665 0.005599 6 1.286558 -0.265574 1.505900 6 1.423296 -1.649210 1.996958 8 3.023602 0.268843 -0.249480 6 3.913431 0.126647 0.761789 8 3.537130 -0.043812 1.925179 6 0.878308 1.270219 -0.522395 8 -0.264467 1.281600 -0.935598 8 -0.553868 -0.892557 0.611830 50 -2.391261 -0.041506 -0.214187 17 -2.146361 -1.478984 -2.152704 9 0.898528 -0.963272 -2.057411 9 2.379910 -2.073493 -0.913377 17 -2.171792 1.567638 1.621320 17 -3.924542 -1.461587 0.937604 17 -3.604522 1.579496 -1.494963 7 5.193558 0.204756 0.355282 6 6.259115 0.176290 1.352749 6 5.590216 0.405906 -1.036757 8 1.633405 2.357929 -0.452837 6 0.986724 3.590454 -0.872362 1 1.727310 4.369175 -0.699822 1 0.721199 3.525719 -1.928604 1 0.085796 3.756967 -0.280030 1 6.808061 1.124945 1.349279 1 5.825113 0.014367 2.337428 1 6.959539 -0.634208 1.125375 1 5.921566 1.437799 -1.202875 1 6.420317 -0.268146 -1.268872 1 4.758993 0.184275 -1.701316 1 0.871200 -3.656374 1.444918 1 1.898594 -1.806266 2.956661 6 1.001046 0.840977 2.448940 1 -0.434214 -2.650430 -0.559476 1 1.335408 0.573123 3.451926 1 1.468141 1.776297 2.137976 1 -0.087019 0.997895 2.474265