We explored the 1,3-olefin transposition of allylbenzene to methyl styrene, where olefin conjugation with the arene would provide a thermodynamic driving force for the reaction. Since we hypothesized the in situ formation of a catalytically active Ru-H species, arising from alcohol dehydrogenation, we initiated our studies using a toluene/isopropanol co-solvent mixture, with Na t OBu as an alkoxide base. Using 4 mol % of 1-RuCl, these conditions enabled the formation of the transposition product in a 52% yield after 2 hours (Table , Entry 1). In contrast to similar methods, using 1-RuCl as a pre-catalyst enabled setup of the reaction in air. Performing the reaction neat in isopropanol greatly enhanced yields (81%; Table 1, Entry 2) even at a lower temperatures (50 o C). Modifications to the ligand scaffold also impacted yields, with catalysts bearing methyl substituents at the 5-and 6-position of the pyridyl groups generating the transposition product in 85% (5-RuCl) and 96% (6-RuCl) yields respectively (Table , Entries 3-4). Decreasing the catalyst loading, base loadings, as well as conducting the reaction at lower temperatures greatly inhibited yields (see supporting information). We hypothesize this arises from lower formation of the reactive [Ru-H] species. Alternatively, to circumvent the need for isopropanol and stoichiometric base, the air-sensitive Ru-H pre-catalysts can be used directly without any additives (83%; Table , Entry 5). Changing the solvent to THF or acetonitrile further improved yields to 91% and 93%, respectively (Table , Entries 6-7). We hypothesize that more highly coordinating solvents encourage the dissociation of the phosphine groups from the catalyst, a necessary step for the reaction to occur. In acetonitrile, excellent yields were maintained even at lower catalyst loadings (2 mol%, 92 %; Table , Entry 8). Interestingly, we observed quantitative yields when the reaction was conducted at room temperature, which may be a consequence of reduced product degradation caused by higher temperatures. These mild conditions were used for expanding the substrate scope, however, we found that high yields can be conserved at even lower catalyst loadings (0.5 mol%) by extending reaction time (16 hours, 87 % -Table , Entry 10). We found that the optimized conditions were tolerant to a variety of allylic, homoallylic and longer chain terminal olefins, providing transposed products in good to excellent yields, with exclusive diastereoselectivity in most cases (Figure ). A range of styrenes were prepared with both electron donating (2c 91 % yield) and electron withdrawing substituents (2e 80 % yield). More sterically encumbering ortho-substituted aromatic systems were compatible, though with slightly diminished diastereoselectivity (2d, 98 % yield (E/Z = 95:5)). Isomerization to afford 2e demonstrated that halogens are tolerated, which are known to be labile functionalities with other metal catalysts like Pd. We also established the ability to transpose olefins over multiple carbon atoms, with both chain-walking products 2f (94 %) and 2g (70 %) being isolated in high yields. Nitrogen heterocycles are also known to be challenging for transposition chemistry due to their coordinating nature, 8,9,15-17 however, pyridine (2l 67 %) and indole (2o 89 %) containing substrates all performed well. Interestingly, for substrates bearing a substituent at the benzylic position, -H elimination from the tertiary site is exceedingly slow. With 2h, we demonstrated that this steric influence can be manipulated to prevent full transposition to the thermondynamically favored styrene, allowing for a selective 1,3-isomerization in this case. Similarly, the -OTES substituted 2i also exhibited slow -H elimination. However, the increased hydricity of this substrate meant the conjugated vinyl silyl ether could be generated at elevated temperatures (56 % yield in toluene at 110 o C), a versatile handle for further functionalization. With the desire to move beyond styrenes, we illustrated that conjugation with heteroatoms are also a sufficient thermodynamic driving force. Vinyl ethers (2m 78 %) and enamines (2n 82 %, 2o 89 %) can all be readily generated under these conditions. Similarly, conjugation with another olefin to furnish dienes are also viable (2j 95%). It is worth noting that O-and N-allyl substrates derived from weak conjugate bases (e.g phenol) could undergo de-allylation over transposition. Under the Ru-Cl conditions described in Table , complete de-allylation can be achieved, which could have application to selective deprotection chemistry. We also observed that allylic alcohols are converted to the corresponding carbonyl compounds presumably a result of first transposing to the respective enol (2r 84 %). Finally, to highlight the versatility of these systems, we conducted one-pot sequential reactions to further functionalize the transposition products. For example, the sequential transposition/Diels-Alder reaction with 1j provided the cycloaddition addition product in excellent yield (3a 87 % over two steps) and diastereoselectivity (91:1).