1,3 -Dienes are important compounds, present in a variety of natural products and bioactive molecules. 1 Moreover, they possess a unique reactivity, which is exploited in a variety of useful transformations such as the Diels-Alder cycloaddition. 2 A variety of methods exist for the construction of 1,3-dienes. However, the synthesis of highly functionalized 1,3-dienes is still challenging. In particular, there are only few general methods for the synthesis of dienes bearing a carbinol function at the  position of the conjugated system, despite the fact that these compounds are versatile building blocks in organic synthesis. One of the main strategies is the addition of organometallic allenyl reagents (M = Si, Sn, B, Cr) to carbonyl compounds (Scheme 1A, Eq. 1). This approach can also be performed enantioselectively. Other reported methods are the enyne metathesis of propargylic alcohols (Scheme 1A, Eq. 2), and the homologation of epoxybromides with sulfur ylides (Scheme 1A, Eq. 3). However, all these methods are mostly used for the synthesis of simple 1,3-butadien-2-yl carbinols, while more substituted dienes are rarely accessible. Therefore, the development of new methods for the synthesis of more substituted dienyl carbinols would be highly desirable. Cyclopropenes are the smallest cyclic alkenes. Due to the substantial ring strain, they display unique reactivity compared to other strained alkenes. In particular, the ring-opening of cyclopropenes with the formation of vinylmetal carbene intermediates represents an important platform for the development of synthetic methods. These versatile intermediates were shown to undergo a variety of transformations including cyclopropanation of alkenes (Scheme 1B, Eq, 1), 9 carbene-carbene coupling (Scheme 1B, Eq. 2), 10 and C-H and X-H insertions (Scheme 1B, Eq. 3). 11 1,3-Dienes can be considered as the isomers of cyclopropenes, and are more stable due to the absence of strain. Surprisingly, only few substrate-specific examples for the energetically-favored catalytic isomerization of cyclopropenes to dienes have been reported: Zhi-Bin Zhu and Min Shi reported a cascade isomerization/Diels-Alder cycloaddition of 1-aryl,2-alkenylcyclopropenes. During completion of our work, the group of Ruben observed the isomerization of cyclopropenyl silane to the corresponding diene product under Pt catalysis as an undesired side reaction. 11d Such isomerization, if performed in a controllable manner, would be highly useful for the synthesis of 1,3dienes, in particular valuable 1,3-dien-2-yl carbinols. Herein, we report our studies on the platinum-catalyzed isomerization of 3,3-disubstituted cyclopropenylcarbinols, easily accessible from addition of cyclopropenyllithiums to carbonyl compounds, to highly substituted conjugated dienes (Scheme 1C). Our group recently became interested in the development of new synthetic methods involving cyclopropenes. While exploring reactions of platinum complexes with cyclopropenylcarbinol 1a we observed the formation of the unexpected diene product 2a (Table , entry 1). Inspired by this result, we decided to optimize this transformation. First, different platinum catalysts were examined, and only PtBr2 gave comparable results (Table , Entries 2-5). Then, different solvents were examined for both PtCl2 (for the results see the SI) and PtBr2 (Table , Entries 6-8). The reaction using PtBr2 in DCE gave the best yield of 60% (Entry 8). Fine-tuning of the reaction temperature and the concentration resulted in a slight improvement of the yield up to 69% (Table , Entry 9). When the reaction was performed with 5 mol% of the catalyst, it was difficult to obtain reproducible results. More reliable yields were obtained using 10 mol% of the catalyst. a The reactions were performed on a 0.1 mmol scale. The yield was determined by 1 H NMR of the concentrated reaction mixture using CH2Br2 as an internal standard. The reaction was performed at 70 °C.