We
report, for the first time, manganese-mediated direct functionalization
of the Hantzsch esters with readily accessible alkyl iodides through
an aromatization–dearomatization strategy. Applying this protocol,
a library of valuable 4-alkyl-1,4-dihydropyridines were facilely afforded
in good yields. This simple and practical reaction proceeds under
visible-light irradiation at room temperature and displays high functional-group
compatibility. Additionally, the method is applicable for gram-scale
synthesis and late-stage functionalization of complex molecules.
A simple and general method for anti-selective hydrosulfonylation of unactivated alkynes with sulfonyl chlorides in the presence of a catalytic amount of phenanthroline-based Lewis base and (Me 3 Si) 3 SiH as the hydrogen atom donor has been developed. The protocol proceeds efficiently under mild and metal-free conditions, delivering a diverse set of (Z)-vinyl sulfones with high stereoselectivity. Additionally, the method displays excellent functional-group compatibility and can be applied to the late-stage modifications of complex drugs and their derivatives. Experimental and density functional theory studies unveiled that the key to the transformation's success is the employment of a phenanthroline-based Lewis base, which interacts with sulfonyl chlorides to form a halogen-bond complex that accelerates the cleavage of the S−Cl bonds of sulfonyl chlorides under the irradiation of visible light.
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