The α-alkylation of ketones is a fundamental synthetic transformation. The development of asymmetric variants of this reaction is important given that numerous natural products, drugs, and related compounds exist as α-functionalized ketones or derivatives thereof. We previously reported our preliminary studies on the development of a new enantioselective ketone α-alkylation procedure using N-amino cyclic carbamate (ACC) auxiliaries. In comparison to other auxiliary-based methods, ACC alkylation offers a number of advantages and is both highly enantioselective and high yielding. Herein, we provide a full account of our studies on the enantioselective ACC ketone α-alkylation method.
Chiral nonracemic N-amino cyclic carbamates (ACCs) are important auxiliaries for certain asymmetric transformations. In the past they have been synthesized from oxazolidinones using methods that require the preparation and use of non-atom economical aminating agents that can be difficult to prepare, and often strong bases. In what follows we describe a mild and operationally simple method for the direct N-amination of oxazolidinones that uses NH2Cl derived from commercial bleach. Chiral nonracemic N-amino cyclic carbamates (ACCs) have gained attention as auxiliaries for important asymmetric transformations. The synthetic utility of these systems was first demonstrated by Friestad in 2000 (Scheme 1a). 1 In that work, hydrazones (5) obtained from the condensation of ACCs and aldehydes were found to undergo diasteroselective radical additions to produce hydrazines (6).
The gastrointestinal tract contains trillions of microorganisms, which are central to human health. Lactobacilli are considered beneficial microbiota members and are often used in probiotics, but their molecular functions, and especially those which are metal-dependent, remain poorly defined.
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