stric hindered postion to give linear products. Moreover, the use of a high oxidative phase of alkenes with a prefuncationalized leaving group (LG) requires of extra steps and limits further applications of the reaction. Thus, direct and selective C-H oxygenation of alkenes with free O-based nucleophiles represents the most ideal solution to allylic ethers due to high atom-economy and simplicity. Over the past years, terminal alkenes have been utilized for the intermolecular coupling with carboxylic acids, alcohols, and other O-based nucleophiles . However, linear products typically are formed dictated by kinetic control . To bypass this challenging issue, internal alkenes are used for the synthsis of branched allylic products by allylic C-H oxygenation. In 2018, Blakey developed Rh-catalzyed intermolecular allylic etherifcation of internal alkenes with alcoholes to branched ethers at 60 o C . Recently, Gevorgyan deveoped an intriguing visible-light mediated Pd-catalzyed allylic C-H oxgenation of internal alkenes at room temperature (Scheme 1c) . This reaction requires stoichiometric aryl bromide as hydrogen atom transfer (HAT) reagent and typically are applied to carboxylic acids, phenols and oximes. In 2014, White group disclosed a branched-selective intramolecular allylic etherification of terminal olefins, which preinstalls alkenes and alcohols into one molecule . To date, direct allylic C-H etherification of alkenes to branched ethers still remains challenging. Moreover, allylic C-H etherification of terminal alkenes to branched allylic ethers imposes additional challenges to overcome the steric hindered effect to achieve the desired regioselectivity. Herein, we report a visible-light and cobalt catalyzed direct allyic C-H oxygenation of terminal alkenes with free alcohols to branched allylic ethers at room temperature (Scheme 1d). The precious-metal-free conditions allows for the allylic C-H oxygenations with various Onuclophiles, such as primary, secondary, tertiary alcohols, caboxylats, oximines and 1,3-diketones. We started to investigate the feasibility of allylic C-H etherification of terminal alkenes using α-butyl styrene (1a) and ethanol (2a, EtOH) as prototype substrates (Table ) . After extensive optimization of different dimentions of reaction parameters, the use of Mes-3,6-t-Bu2-Acr-Ph + BF4 -(1 mol%) as photocatalyst, Co(dmgH)(dmgH2)Cl2 (9 mol%) as catalyst, KHCO3 (20 mol%) as additive in 1, 2dichloroethane (DCE, 0. 5 M) under the irradiation of blue LEDs at room temperature for 18 h was defined as standard conditions, delivering the direct ethoxylation of allylic C-H of 1a to give branched allylic ether (3a) in 86% isolated yield (Table , entry 1). Other acridinum-based and Ir-based photocatalysts could also mediate the desired process, albeit leading to the formation of 3a in inferior yields (Table , enties 2-5). Other hydrogen evolving catalysts proved to be less effective, delivering 3a in 22-79% yields (Table , enties 6-9). In addition, it was found that the judicious selection of solvent was crucial for the success of the desired direct oxygenation of allylic C-H bond, giving optimal result using 1,2dichloroethane as solvent (Table , entries 10-12). The use of base as additive enhanced the reactivity of the reaction, decreased yields of 3a were obtained (72% and 80%) using other base as additive furnished (Table , No light/PC/[Co] 0% a Reaction was conducted using 1a (0.1 mmol) and 2a (0.3 mmol) under indicated conditions. PC = photocatalyst. b Yield was determined by 1 H NMR based on crude mixture of the reaction using mesitylene as internal standard. Isolated yield is shown in the parentheses With the optimized conditions in hand, we set to explore the scope of this dual catalyzed direct C-H bond etherification at room temperature to branched allylic ethers (Scheme 2). First, the scope of alkenes was investigated. A wide range of terminal styrenes were well-tolerated in the reaction to give corresponding allylic C-H etherification products (3b-3t) in the presence of ethanol in good yields.