A Novel Synthesis of 1-Isochromanols via Hetero Diels-Alder Reaction of Carbonyl Compounds with 1-Trimethylsilyloxy-benzocyclobutene as a Precursor of α-Oxy-o-Quinodimethane Under Mild Condition

Reaction of 1-trimethylsilyloxybenzocyclobutene(1) with carbonyl compounds catalyzed by tris(dimethylamino)sulfur (trimethylsilyl)difluoride (TASF) at room temperature gave 1-isochromanol derivatives as corresponding hetero Diels-Alder adducts in good yields.     

Analysis of Off-Axial Optical Systems (1)

We have established a new method of aberration analysis for off-axial optical systems which are generalized concepts of co-axial optical systems, by introducing two kinds of newly defined 4-element vectors and expanding these vectors with the help of tensor algebra. In this method, since aberration properties are represented in tensor form, we can easily formulate the aberration relations between different azimuths. We can then evaluate the azimuth dependence of aberration properties in greater detail by separating them into inherent optical properties parts, which are independent of azimuths, and the paraxial ray-tracing part, which includes the expression of the evaluation azimuth.     

Effect of the degree of polynomials in the Savitzky—Golay method for calculation of second-derivative spectra

The second-derivative spectra of absorption curves simulated by a Gaussian function were obtained by using Savitzky—Golay cubic (CPC) and quintic polynomial convolutions (QPC), based on 17 points assumed to be at 0.25-nm intervals. For data obtained directly from the simulated curves (real-type data), the second derivatives agreed with the true values if the widths at half height of the peaks were > 15 nm for CPC and 5 nm for QPC. But when integer values obtained from the real-type data were used to simulate a 12-bit A/D conversion, considerable noise appeared on the second-derivative spectra of peaks wider than the above values, obtained by both CPC and QPC. This occurred because the rounding errors introduced by the A/D conversion formed small shoulders on the digitally reproduced absorption curves, which were enhanced by the differentiation to generate noise. The noise was more intense in QPC than in CPC, thus CPC is preferable for peaks that are not very narrow.     

Addition of alkyl radicals, generated from carboxylic acids via photochemical decarboxylation, to glyoxylic oxime ether: a mild and efficient route to α-substituted α-aminoesters

Radical addition to a glyoxylic oxime ether was accomplished under mild conditions using an alkyl radical generated from a free carboxylic acid via photochemical decarboxylation. The photoreaction provided an efficient route to α-substituted α-aminoesters from carboxylic acids and oxime ether.