The growing study of glycobiology [1] has led to an increased focus upon carbohydrate architecture [2] as an important platform for reaction design and methodological advancement. [3] Application of the aldol reaction [4] to the synthesis of carbohydrates is well-documented; [5] however, the attendant need for protection-group manipulations and oxidation-state adjustments has thus far precluded a broadly utilizable protocol. Intriguingly, a highly expedient two-step carbohydrate synthesis can be envisioned based on an iterative aldol sequence using simple a-oxyaldehydes [Eq. (1)]. While attractive in theory, the practical execution of this carbohydrate strategy would require the invention of two new aldol technologies: a) an enantioselective aldol union of a-oxyaldehyde substrates (Aldol step 1) and b) a diastereoselective aldol coupling between tri-oxy substituted butanals and an a-oxyaldehyde enolate (Aldol step 2). Herein we report the successful development of the first enantioselective organocatalytic coupling of an a-oxyaldehyde (Aldol step 1). This new aldol reaction provides an operationally simple protocol for the stereocontrolled production of polyol architectures and sets the stage for a twostep enantioselective carbohydrate synthesis. [6] The development of a direct, enantioselective catalytic aldol reaction between a-oxyaldehyde substrates (Aldol step 1) is dependent upon three key issues of chemical selectivity. [7] In addition to the traditional requirements of absolute and relative stereocontrol comes the chemoselective constraint that the a-oxyaldehyde reagent A must readily participate as both a nucleophilic and electrophilic coupling partner while the a-oxyaldehyde product B must be inert to in situ enolization or carbonyl addition [Eq. (1)]. Recently, we disclosed an organocatalytic strategy for the highly regioselective, diastereoselective, and enantioselective aldol cross-coupling of a-alkyl-bearing aldehydes [Eq. (2)]. [8] An important feature of this transformation is that the enantioenriched aldehyde products C do not participate in further aldol reactions (by either enamine formation or carbonyl addition). With this in mind, we hoped that such remarkable catalyst-controlled stereo-and chemoselectivity might be extended to the union of a-oxygenated aldehydes [Eq. (3)], thereby allowing the first step in a two-step carbohydrate synthesis to occur [Eq. 1].Our enantioselective organocatalytic a-oxyaldehyde coupling was first examined using l-Proline (10 mol %) and a

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An uncharged host 6 for selective binding of chloride is described. This host features a triazine-trione platform, three short side-arms which are conformationally preorganised relative to the platform, and p-nitrophenylsulfonamide groups for hydrogen-bonding to anions. Host 6 binds chloride with K % 150 000 M À1 in CHCl 3 and shows a chloride/nitrate selectivity of 10 2 .

Enantioselective Organocatalytic Direct Aldol Reactions of α-Oxyaldehydes: Step One in a Two-Step Synthesis of Carbohydrates. -The title reaction offers a new and simple method for the stereoselective formation of polyol compounds. The electronic nature of O-protecting group has an important effect on this coupling. Enantioselective cross-coupling of α-oxyaldehydes and α-alkyl substituted aldehydes is also possible under these conditions. -(NORTHRUP, A. B.; MANGION, I. K.; HETTCHE, F.; MACMILLAN*, D. W. C.; Angew.

Simply peel off the layers: Functionalities from nature may be used to meet the demands of contemporary materials science in terms of the efficient and safe production of high‐quality, versatile materials. Thus, the spontaneous absorption on graphite of small amphiphilic proteins known as hydrophobins from an aqueous phase, followed by sonication, led to the exfoliation and stabilization of graphene sheets (see picture).