Enantioselective Syntheses of Ring-C Precursors of Vit. B₁₂. Reagent Control

Enelactones of the general structure S-(−)-I were prepared in three steps from alcohol 21 and acids 22 (ee ≈ 85%). Lactones S-(−)-I are versatile precursors to enelactams II of the type found in Vitamin B12

Synthesis of Porphobilinogen via a Novel Ozonide Cleavage Reaction

Porphobilinogen lactam methyl ester (3a) has been prepared in seven steps, and ∼20−30% overall yield, beginning with furfurylamine (4a). Hydrolysis of 3a following the literature procedure then gave porphobilinogen (1). A key intermediate in our synthesis of 3a is the 7-oxonorbornene derivative 7a, which was derived from 4a utilizing a tandem Johnson ortho ester Claisen rearrangement followed by intramolecular Diels−Alder cyclization (five steps, 55−65%). Interesting steric accelerating effects were observed in this sequence. Conversion of 7a to 3a was then accomplished employing a novel ozonide cleavage/oxidation reaction, which generated tetrahydrofurans 16a, 32, and 33 in the proper oxidation state for direct aminolysis to pyrrole 3a. A mechanism is proposed for the ozonide cleavage/oxidation that accounts for the observed stereoselectivity of this step

Experimental results for another access log file (<i>N</i> = 20,000).

<p>Experimental results for another access log file (<i>N</i> = 20,000).</p

Origami Paper-Based Stretchable Humidity Sensor for Textile-Attachable Wearable Electronics

Flexible and stretchable humidity sensors for wearable purposes have become increasingly important in health care and physiological signal monitoring. However, to the authors’ knowledge, there is no report on flexible and stretchable paper-based humidity sensors that are low-cost, easily fabricated, and environmentally friendly. In this work, for the first time, we propose a stretchable, textile-compatible paper-based origami humidity sensor (POHS). The POHS can achieve good stretchability by integrating origami folding structures with a paper substrate, in which an airlaid paper acts as both a sensing material and a sensor substrate. This sensor has high sensitivity, good response, and recovery properties with excellent stability during deformation. This sensor has proved to be capable of dynamically monitoring the breathing rate after 300 folding and unfolding cycles. The flexible and stretchable nature of our POHS ensures that it is compatible for textile attachment and its utility for wearable applications, including respiration rate monitoring and diaper wetting detection. The facile fabrication process and convenient disposal method of the POHS proposed in this study provide feasible solutions for the development of low-cost wearable humidity sensors

Comparison of <i>TPAP</i> results for different access log files (<i>N</i> = 10,000) (each plot, A-D, represents a different access log file).

<p>Comparison of <i>TPAP</i> results for different access log files (<i>N</i> = 10,000) (each plot, A-D, represents a different access log file).</p

Comparison of <i>TPAP</i> results for various values of <i>N</i> (<i>m</i> = 10).

<p>Comparison of <i>TPAP</i> results for various values of <i>N</i> (<i>m</i> = 10).</p

The performance improvement achieved using the copy storage strategy with various <i>CR</i>s (<i>N</i> = 10,000).

<p>The performance improvement achieved using the copy storage strategy with various <i>CR</i>s (<i>N</i> = 10,000).</p

Adaptability experiment based on the INS dataset (<i>N</i> = 20,000).

<p>Adaptability experiment based on the INS dataset (<i>N</i> = 20,000).</p

Comparison of <i>TPAP</i> results at various scales of <i>m</i> (<i>N</i> = 10,000).

<p>Comparison of <i>TPAP</i> results at various scales of <i>m</i> (<i>N</i> = 10,000).</p

The datasets used in this analysis.

<p>^aAll data were relabeled with natural numbers ranging from zero to the length of the dataset.</p><p>^bEach access sequence recorded only the labels of the data in chronological order.</p><p>^* As stated in section 4.1, only of the 20% files will be requested.</p><p>^** All files will be requested.</p><p>The datasets used in this analysis.</p