New 2,10-Functionalized Camphor Derivatives

Synthetic routes to precursors of tricyclic camphor derivatives fused at the 2,10-positions, the corresponding halohydrins and dimethyl acetal, are discussed.     

Synthesis of New Functionalized Organophosphorus Acids and their Derivatives

Abstract

Functionalized organophosphorus acids and their derivatives are of great interest as chelating ligands, bioactive substances with various properties and the key compounds for the synthesis of phosphorus containing peptides. We have developed the convenient methods of the synthesis of new functionalized organophosphorus acids and their derivatives using a series of PH-acids and their esters with highly reactive fragments PH and POSi as well as phosphorus containing arnines with fragments PCHNH and PCHNSi. These organophosphorus synthons react smoothly with α-heterosubstituted derivatives of various amines and amides, functionalized alkenes and their oxides, as well as with acyl and sulfonyl chlorides giving the perspective compounds with high yields. New available types of new functionalized organophosphorus acids and their derivatives are presented below.     

Chiral Camphor Derivatives as New Catalysts for Asymmetric Phase‐Transfer Alkylation

The synthesis of new chiral phase‐transfer catalysts based on the optical camphor is described. The alkylation of the benzophenone imine of glycine tert‐butyl ester with benzyl bromide in the presence of new chiral phase‐transfer catalysts afforded the desired alkylation product in good yields and up to 39% ee.     

Synthesis of Functionalized Dihydrofurocoumarin Derivatives from 3-Aminoalkyl-4-hydroxycoumarin

Some dihydrofuro-fused coumarin derivatives were synthesized from 3-aminoalkyl-4-hydroxycoumarin via in situ generation of N-ylide. The 3-aminoalkylated 4-hydroxycoumarin derivatives were synthesized from one-pot, three-component reaction of 4-hydroxycoumarin, aryl aldehydes, and secondary amines in ethanol at room temperature. Again, when salicylaldehyde was employed instead of benzaldehyde, interestingly pyranocoumarins were obtained. The reaction protocol can be further explored toward the synthesis of many other heterocyclic fused dihydrofurans.     

New C(4)‐Functionalized Colchicine Derivatives by a Versatile Multicomponent Electrophilic Aromatic Substitution

Electrophilic alkylation of colchicine at C(4) was accomplished by a multicomponent aromatic electrophilic substitution reaction with electrophilic aldehydes and carboxylic acids or amides in H₂SO₄. A series of new derivatives were obtained and evaluated for their antiproliferative effect towards various tumor cell lines, and their stimulatory effect on the development of polarity in human neutrophils.     

Ring-Closing Metathesis of Functionalized Acetylene Derivatives: A New Entry into Cycloalkynes

A tungsten alkylidyne catalyst is the key to achieving ring-closing metatheses of diynes to form functionalized macrocycles [Eq. (a)]. Partial reduction of the cycloalkynes provides stereoselective Z-configured cycloalkenes, which are currently inaccessible by conventional alkene metathesis.     

Synthesis of Highly Functionalized Cyclobutene Derivatives

Summary. Protonation of the reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates with CH-acids, such as ethyl 2,4-dioxo-hexanoate and ethyl 2,4-dioxo-5-methylhexanoate, lead to vinyltriphenylphosphonium salts, which undergo an intramolecular Wittig reaction to produce cyclobutene derivatives in fairly high yields.Received November 8, 2002; accepted November 29, 2002 Published online July 3, 2003     

Boron Clusters as a Platform for New Materials: Synthesis of Functionalized o‐Carborane (C2B10H12) Derivatives Incorporating DNA Fragments

A synthetic strategy for functionalization of the three vertices of o‐carborane and the attachment of the obtained triped to the solid support was developed. Further functionalization of the triped with short DNA sequences by automated DNA synthesis was achieved. The proposed methodology is a first example of boron cluster chemistry on a solid support opening new perspectives in boron cluster functionalization.     

Synthesis and Phosphorylation of 2- and 3-Halomethyl Derivatives of Functionalized 2-tert-Butylfurans

2-Halomethyl derivatives of 3-functionalized 5-tert-butylfurans are phosphorylated underconditions of the Michaelis-Becker, Arbuzov reactions similarly to other halomethylfurans. No effectof the tert-butyl substituent on the yield of the reaction products was found in this case. Contrary to that, the2-methoxymethyl derivative of 3-chloromethyl-5-tert-butylfuran proved to be more thermostable than its analog containing no tert-butyl substituent. As a result, the yield of phosphonate in the Michaelis-Becker reaction under similar conditions increases 2.5 times. The observed stabilization of the furan ring is explained by shielding of its oxygen atom by the tert-butyl group.     

Synthesis and Antiviral Activity of N-Heterocyclic Hydrazine Derivatives of Camphor and Fenchone

Chemistry of Heterocyclic Compounds - Alkylation of the primary amino group of hydrazones of (+)-camphor and (–)-fenchone with dihaloalkanes leading to the production of novel...     

Diastereoselective Synthesis of Highly Functionalized Proline Derivatives

An efficient way to access highly functionalized proline derivatives was developed based on a Cu(I)-catalyzed reaction between CF₃-substituted allenynes and tosylazide, which involved a cascade of [3 + 2]-cycloaddition/ketenimine and a rearrangement/Alder-ene cyclization to afford the new proline framework with a high diastereoselectivity.     

Sulfonyl Azoles in the Synthesis of 3‐Functionalized Azole Derivatives

Sulfonyl indoles, as well as related azolyl derivatives, have been recently introduced in synthesis as stable precursors of reactive indolenine intermediates. This personal account reports on the discovery of sulfonyl azoles and their practical utilization in many synthetic processes for the preparation of functionalized 3‐substituted indoles, indazoles, and pyrroles. The indolenine intermediates obtained by treatment of sulfonyl azoles with Brønsted bases or Lewis acids can be considered as vinylogous imino derivatives that can be made to react with different nucleophilic reagents. These include organometallic reagents, reducing agents, stabilized carbanions, and heteronucleophiles. The controlled and mild conditions for the generation of indolenines from sulfonyl azoles make these substrates particularly useful in asymmetric synthesis, exploiting organo‐ or metal‐catalyzed processes. Although less exploited, sulfonyl indoles can also be involved in photochemical processes for the preparation of polycyclic derivatives.

     

群柱虫内酯官能团化的C2-C10片段的立体选择性合成

本文以廉价的消旋甲基戊二酸酐为起始原料,完成了具有抗肿瘤活性的海洋天然产物群柱虫内酯（Clavulactone）官能团化的C2-C10片段的立体选择性合成。使用的关键方法包括不对称去对称化获得光学纯手性孤立甲基,和RCM方法构建顺式烯烃。该片段的获得为群柱虫内酯的全合成提供了基础。