A Simple and Practical Synthetic Protocol for Acetalisation, Thioacetalisation and Transthioacetalisation of Carbonyl Compounds under Solvent-Free Conditions
作者:Abu T. Khan、Ejabul Mondal、Subrata Ghosh、Samimul Islam
Direct anodic (thio)acetalization of aldehydes with alcohols (thiols) under neutral conditions, and computational insight into the electrochemical formation of the acetals
A versatile protocol for the production of acetals/thioacetals by means of direct electrochemical oxidation is developed here under neutral conditions, providing (thio)acetals with good functional group tolerance and a wide scope for both aldehydes and (thio)alcohols. DFT calculations reveal that direct electron transfer from the anode plays a key role in carbonyl activation during this acid free acetalization
Selective desulfurization of 2-alkyl-1,3-dithianes, -oxathiolanes, or -thiazolidines 1 with one equivalent of tri-n-butyltin hydride yields acyclic compounds R1R2CHX(CH2)nSSnBu3 (X = S,O,NH; n= 2,3), (2) which can be destannylated to the corresponding mercaptans 3.
用一当量的氢化三正丁基锡对2-烷基-1,3-二硫杂环丁烷,-氧杂硫杂环戊烷或-噻唑烷1进行选择性脱硫,得到无环化合物R 1 R 2 CHX(CH 2)n SSnBu 3(X = S, O,NH; n = 2,3),(2),其可被脱甲锡化为相应的硫醇3。
Activation and synthetic applications of thiostannanes. Conversion of aldehydes and acetals into 1,3-dithianes with high chemodifferentiation
Novel method for transforming aldehydes and acetals into 1,3-dithianes has been achieved with the aid of organotin thioalkoxides and organotin triflates. Under these reaction conditions, various acid-sensitive groups are tolerated. Differentiation between aromatic or aliphatic aldehydes and acetals has been realized.
Two novel, non-thiolic, odorless dithiol equivalents, α,α-diacetyl cyclic ketene dithioacetals 2a and 2b, had been developed. A range of carbonyl compounds 3 were converted into corresponding dithioacetals, dithianes 4 and dithiolanes 5, in high yields (up to 99%) in the presence of 2a or 2b. Moreover, 2a and 2b show high chemoselectivity between aldehyde and ketone in thioacetalization.