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N-Heterocyclic carbene (NHC) catalyzed transformations have emerged as powerful tactics for the construction of complex molecules. Since Stetter’s report in 1975 of the total synthesis of cis-jasmon and dihydrojasmon by using carbene catalysis, the use of NHCs in total synthesis has grown rapidly, particularly over the last decade. This renaissance is undoubtedly due to the recent developments in NHC-catalyzed reactions, including new benzoin, Stetter, homoenolate, and aroylation processes. These transformations employ typical as well as Umpolung types of bond disconnections and have served as the key step in several new total syntheses. This Minireview highlights these reports and captures the excitement and emerging synthetic utility of carbene catalysis in total synthesis.

Lewis acid activation with N-heterocyclic carbene (NHC) catalysis has presented new opportunities for enantioselective reaction development. Recent findings illustrate that Lewis acids can play an important role in homoenolate annulations by: enhancement of the reactivity, reversal of the diastereo- or regioselectivity, and activation of previously inactive electrophiles. Additionally, the incorporation of a Lewis acid into Brønsted base-catalyzed conjugate addition allowed for an increase in yields.

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A cooperative catalysis approach for the enantioselective formal [3+2] addition of α,β-unsaturated aldehydes to isatins has been developed. The N-heterocyclic carbene (NHC)-catalyzed homoenolate annulations of β-aryl enals require the addition of lithium chloride for high levels of enantioselectivity. This NHC-catalyzed annulation provides efficient access to the 3-hydroxy indole skeleton and has been applied to the first eantioselective total synthesis of maremycin B.

CHANGES IN THE GINGIVAL TISSUES during pregnancy have been termed "pregnancy gingivitis." During this period, the gingiva may appear hyperemic and enlarged and bleeding may be frequent during brushing or on external manipulation. Histopathologic evidence suggests that the microscopic changes observed in the gingiva during pregnancy do not differ from the microscopic changes observed in gingivitis in nonpregnant females. It is suggested that an accentuated inflammatory response to local irritants during pregnancy is the basic cause for the altered appearance of the gingival structures. Löe et al, in a cross-sectional study, examined 121 pregnant and 61 postpartum women. He reported that 100 percent of the women examined during pregnancy and postpartum demonstrated gingival changes which at the clinical level can be adequately described as inflammation of the gingiva (gingivitis), and that the severity of these changes were significantly higher in pregnant than in postpartum patients. The purpose of this investigation was to apply longitudinal epidemiologic techniques to:1. Measure the prevalence of periodontal disease during pregnancy and postpartum. Document the gingival and periodontal changesduring pregnancy and postpartum. 3. Determine what influence, if any, the gingival changes have on the underlying periodontium during pregnancy. 4. Document the presence of hard and soft irritants in the mouth during pregnancy and postpartum. 5. Determine what role local irritants play in the etiology of periodontal disease during pregnancy and postpartum.

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Conjugates between proteins and small molecules enable access to a vast chemical space that is not achievable with either type of molecule alone; however, the paucity of specific reactions capable of functionalizing proteins and natural products has presented a formidable challenge for preparing conjugates. Here we report a strategy for conjugating electron-rich (hetero)arenes to polypeptides and proteins. Our bioconjugation technique exploits the electrophilic reactivity of an oxidized selenocysteine residue in polypeptides and proteins, and the electron-rich character of certain small molecules to provide bioconjugates in excellent yields under mild conditions. This conjugation chemistry enabled the synthesis of peptide-vancomycin conjugates without prefunctionalization of vancomycin. These conjugates had enhanced in vitro potency for resistant Gram-positive and Gram-negative pathogens. Additionally, we showed that a 6 kDa affibody protein and a 150 kDa IgG antibody could be modified without diminishing bioactivity.