SHORT COMMUNICATION DOI: 10.1002/ejoc.201500155 Organocatalyzed Enantioselective Allylation of Isatins by Using a Chiral Amino Alcohol Derived Squaramide as Catalyst [‡] Debashis Ghosh, [a,b] Naveen Gupta, [a,b] Sayed H. R. Abdi,* [a,b] Sekhar Nandi, [a,b] Noor-ul H. Khan, [a,b] Rukhsana I. Kureshy, [a,b] and Hari C. Bajaj [a,b] Keywords: Organocatalysis / Enantioselectivity / Allylation / Isatins / Squaramides A series of new squaramide-based organocatalysts were syn- thesized from commercially available 3,4-dimethoxycyclo- but-3-ene-1,2-dione in two steps. A 2.5 mol-% loading of the organocatalyst successfully catalyzed the asymmetric allyl- Introduction Optically active oxindole derivatives, which have found widespread uses in natural product, agricultural and pharmaceutical chemistry, [1] are important building blocks for various biologically active compounds. [2] In addition, the alkene functionality in 3-allyl-3-hydroxyoxindole can be utilized to synthesize desired organic molecules. [3,4] In the last few years, various metal-based efficient catalytic systems were reported [5] [Equation (1)] for enantioselective allylation of isatins; however, an organocatalyst version had remained unexplored for this type of substrates, although very recently an organocatalytic asymmetric allylation of isatins has been reported by Hoveyda et al. [6] In our quest to develop a new and efficient metal-free catalytic system for the asymmetric allylation reaction of isatins with allyltin or allylsilane compounds, we are now reporting for the first (1) [‡] CSIR-CSMCRI registration number 008/2015 [a] Discipline of Inorganic Materials and Catalysis, CSIR – Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI) G. B. Marg, Bhavnagar 364021, Gujarat, India E-mail: shrabdi@csmcri.org http://chiralgroups.webs.com/ [b] Academy of Scientific and Innovative Research, CSIR – Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), G. B. Marg, Bhavnagar 364021, Gujarat, India Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/ejoc.201500155. Eur. J. Org. Chem. 2015, 2801–2806 © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 2801 ation of isatins with allyltributyltin to give the corresponding 3-allyl-3-hydroxyoxindoles in high yields and enantio- selectivities (up to 98 % ee). time a chiral squaramide as organocatalyst for the enantio- selective allylation of isatins [Equation (2)]. (2) Prior works on organocatalysts for different organic transformations had revealed that the presence of key features such as the ability to act as hydrogen-bond donor or the presence of one or more chiral centres with critical and desired electronic environments are necessary to affect high reaction rate and stereoinduction. Organic molecules having a squaramide [7] or thiourea [8] skeleton have these de- sired features; therefore, for the present study we have syn- thesized a series of thiourea- (Scheme 1) as well as squar- amide-based (Scheme 2) organocatalysts (Figure 1) and Scheme 1. Synthesis of thiourea-based organocatalysts 1–2.