Scheme 2. Examples for the use of cyclic N,O-acetals as a stereocontrol element. a) For dihydroxylation. b) For epoxidation. c) For hydrogenation. NMO = N-methylmorpholine-N-oxide, THF = tetrahydrofuran. Scheme 3. Examples for the use of cyclic N,O-acetals as a diversitygenerating element. TBS = tert-butyldimethylsilyl.

We report the intramolecular charge-transfer (ICT) dynamics of 1-tert-butyl-6-cyano-1,2,3,4-tetrahydroquinoline (NTC6), a planar analogue of 4-(dimethylamino)benzonitrile (DMABN), by using time-resolved fluorescence (TRF) and TRF spectra (TRFS). TRFS allow accurate determination of the ICT dynamics free from the spectral relaxation caused by the solvation and vibronic relaxation. For NTC6 in tetrahydrofuran (THF), the locally excited (LE) state is populated exclusively presumably via a conical intersection from the initial photoexcited S2 (La) state, and the LE state undergoes ICT single exponentially with a time constant of 1.8 ± 0.2 ps. In acetonitrile, however, both LE (22%) and ICT (78%) states are populated from the S2 state, and the population in the LE state undergoes ICT in 800 ± 100 fs. The ICT state undergoes further relaxation in 1.2 ps along the solvation and the intramolecular nuclear coordinates involving the rotation of the amino group to form a twisted ICT state. Coherent nuclear wave packet motions of 130 cm(-1), which can be assigned to the -C≡N group bending mode, were observed in the TRF of the reactant (LE) and product (ICT) states, indicating that the ICT reaction is partially coherent. Compared with DMABN, the ICT dynamics of NTC6 are quite homogeneous, and we speculated on the narrow conformational distribution of NTC6 in the ground state along the rotation of the amino group due to its rigid structure.

The Au(I)-catalyzed reactions of 5-allyloxy-1-ynes gave various γ-hydroxyketones, via a hydration-terminated domino sequence involving sigmatropic allyl migration as the key event. Moreover, the scope of the sigmatropic allyl transfer was systematically determined.

Ringbildung: Eine neue Strategie zur Synthese cyclischer Amine nutzt ein stereochemisch definiertes cyclisches N,O‐Acetal als wichtigstes stereokontrollierendes und Diversität erzeugendes Element. Das Acetal, das seine stereochemische Integrität über alle katalytischen Umwandlungen bewahrt, wurde durch asymmetrische Hydroaminierung eines Alkoxyallens mit dem chiralen Liganden L* und anschließende Ringschlussmetathese erhalten.

Synthetic Strategy for Cyclic Amines: A Stereodefined Cyclic N,O-Acetal as a Stereocontrol and Diversity-Generating Element. -A new and efficient method to prepare various optically active cyclic amines is reported. The key steps are stereoselective coupling of aminoalkenes with alkoxyallenes giving chiral N,O-acetals such as (III) and (XIII) and ring-closing metathesis of the latter. -(KIM, H.; LIM, W.; IM, D.; KIM, D.-G.; RHEE*, Y. H.; Angew. Chem., Int. Ed. 51 (2012) 48, 12055-12058, http://dx.