In humans, 5' m(7)G cap addition is accomplished cotranscriptionally by the sequential action of the capping enzyme (Hce1) and the cap methyltransferase (Hcm1). We found that guanylylation and methylation occur efficiently during transcription with t(1/2)'s of less than 15 and 70 s, respectively. A two to four order of magnitude increase was found in the rate of guanylylation of RNA in transcription complexes compared to free RNA. This stimulation required only the RNA polymerase II elongation complex and Hce1. Capping activity was weakly associated with elongation but not preinitiation complexes. The CTD was not required for functional coupling but stimulated the rate of capping 4-fold. Inhibition of Cdk7 but not Cdk9 similarly slowed the rate of capping.

Direct acyl radical formation of linear aldehydes (RCH2-CHO) and subsequent hydroacylation with electron-deficient olefins can be effected with various types of metal and nonmetal catalysts/reagents. In marked contrast, however, no successful reports on the use of branched aldehydes have been made thus far because of their strong tendency of generating alkyl radicals through the facile decarbonylation of acyl radicals. Here, use of a hypervalent iodine(III) catalyst under visible light photolysis allows a mild way of generating acyl radicals from various branched aldehydes, thereby giving the corresponding hydroacylated products almost exclusively. Another characteristic feature of this approach is the catalytic use of hypervalent iodine(III) reagent, which is a rare example on the generation of radicals in hypervalent iodine chemistry.

Scheme 2. Proposed pathway for the formation of iodanyl radical. Scheme 3. Oxidation of methyl valerate with 2 and 3 d.Scheme 4. Hypervalent iodine(III) reagents 3. [12] naph = naphthalene.

Asymmetric conjugate addition of α-heterosubstituted aldehydes such as α-amido and α-alkoxy aldehydes to vinyl sulfone was effected under the influence of structurally rigid trans-diamine-based Tf-amido organocatalyst (S,S)-2 with a dihydroanthracene framework to furnish α,α-dialkyl(amido)aldehydes and α,α-dialkyl(alkoxy)aldehydes with high enantioselectivity. The chiral efficiency of the structurally unique catalyst (S,S)-2 is apparent in comparison with (S,S)-1 and (S,S)-4 with similar functionality.

A strategy is described for modular catalyst development based upon metal-directed self-assembly of bifunctional subunits around a structural metal to form a heteroleptic complex in which a second set of ligating groups are now suitably disposed to bind a second metal to form a catalytic site. A library of chiral diphosphites was prepared via metal-directed self-assembly and used in a simple asymmetric allylic amination, giving enantiomeric excesses as high as 97%.