Water enabled a highly atom- and step-economical, redox-neutral 4-step cascade process, including SNAr/Knoevenagel condensation/[1,5]-hydride transfer cyclization, to construct pharmaceutically important tetrahydroquinoline spiro compounds efficiently.
An environmentally benign cascade redox-neutral process was developed for the efficient construction of pharmaceutically significant spirocyclic tetrahydro-quinolines via a 3-step cascade Knoevenagel condensation/[1,5]-hydride transfer/cyclization, which features green and additive-free conditions, wide substrate scope, and high step- and atom-economy.
The
scandium-catalyzed redox-neutral cascade [1,5]-hydride transfer/cyclization
between C4-amine-substituted isatins and 1,3-dicarbonyl compounds
has been developed. This protocol enabled the synthesis of tricyclic
[3,4]-fused oxindoles in good to high yields and excellent diastereoselectivities,
featuring high atom- and step economy as well as good functional group
tolerance.
The hydride transfer involved redox-neutral
cascade cyclization
has been developed to construct the spirocyclic bisoxindoles featuring
a [3,4]-fused oxindole moiety from rationally designed C4-amine-substituted
isatins, affording the diverse tricyclic [3,4]-fused oxindoles with
three consecutive chiral centers in good yields and excellent diastereoselectivities
(>20:1).
Sensitivity table method (STM), which is a most widely used computer-aided alignment technology in optical system alignment, faces a problem that is how to determine the correctness of the applied object and established sensitivity table. In order to solve the problem, two criteria for applying STM correctly are concluded, one is determining the linearity relation between misalignments and wavefront aberration, the other one is establishing the effective sensitivity table by monitoring its condition number. Two optical systems are tested in this paper, and experimental results show the correctness of the proposed method.
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