We consider the asymptotic behavior of the global solutions to the initial value problem for the generalized KdV-Burgers equation. It is known that the solution to this problem converges to a self-similar solution to the Burgers equation called a nonlinear diffusion wave. In this paper, we derive the optimal asymptotic rate to the nonlinear diffusion wave when the initial data decays slowly at spatial infinity. In particular, we investigate that how the change of the decay rate of the initial value affects the asymptotic rate to the nonlinear diffusion wave.

We consider the large time asymptotic behavior of the global solutions to the initial value problem for the nonlinear damped wave equation with slowly decaying initial data. When the initial data decay fast enough, it is known that the solution to this problem converges to the self-similar solution to the Burgers equation called a nonlinear diffusion wave, and its optimal asymptotic rate is obtained.In this paper, we focus on the case that the initial data decay more slowly than previous works and derive the corresponding asymptotic profile. Moreover, we investigate how the change of the decay rate of the initial values affect its asymptotic rate.

Iodocyclization of silyl group‐substituted homopropargylic carbamates and amides proceeded via 6‐exo‐dig mode to afford 6‐vinylene‐4,5‐dihydro‐1,3‐oxazines in moderate to quantitative yields. This is the first report for silyl group‐solely directed iodocyclization of alkynes utilizing the β‐silyl effect. Under these mild reaction conditions, various functionalities such as secondary alcohol, acetal, urea, and sulfide were tolerated.

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