Stereo‐Defined Synthetic Route to ( E )‐ and ( Z )‐Tamoxifen Derived from( E )‐1‐Bromo‐2‐iodoalkenes

Stereoselective Synthesis of Silylated Vinylboronates by a Boron-Wittig Reaction and Their Application to Tetrasubstituted Olefins

The highly stereoselective synthesis of a series of tetrasubstituted mono- as well as disilylated vinylboronates is reported by using the boron-Wittig approach. The condensation between acylsilanes and gem-diborylalkanes gave the desired tetrasubstituted olefins in good to excellent yield and high stereoselectivity. Also, a series of trisubstituted silylated vinyl MIDA-boronates was synthesized by using the boron-Wittig reaction followed by a transesterification reaction. This methodology allows direct incorporation of B(pin) and TMS groups in the anti-position of the olefin in a highly stereoselective manner. Further, sequential Suzuki coupling reaction with the silylated vinyl boronic esters generated all-carbon tetrasubstituted alkenes, which have been applied in the total synthesis of the anticancer drug Tamoxifen and aggregation-induced luminogen agent TPE-TF17.

Synthesis of Tetrasubstituted 1,4-Dicarbonyl (Z)-2,3-Dihaloalkenes via Electrophilic Halogenation of Alkynyl Hydrazones

A highly practical and stereoselective route to 1,4-dicarbonyl 2,3-dihaloalkenes is presented. The strategy involves bench-stable unprotected alkynyl hydrazones and commercially available N-halosuccinimides that provide γ-oxo-α,β-(Z)-dihaloenoates in excellent yields with complete Z-selectivity. The protocol also furnishes vicinal dihaloalkenes with two different halogen atoms. Also, a straightforward one-pot synthesis of dihaloenoates from readily accessible 2-oxo-3-butynoate is demonstrated. In addition, potential synthetic transformations of 4-oxo-2,3-dibromoenoates are explored, which include the synthesis of valuable five- and six-membered heterocycles.

Design, synthesis, and biological evaluation of indole-modified tamoxifen relatives as potent anticancer agents

Modulation of existing drugs is an attractive strategy to achieve improved activity in cancer therapy by lowering their effective dose. Preparation of relatives has been suggested and explored to improve the therapeutic effect of anticancer agents. In the current study, we attempted to modulate tamoxifen (TMX) by replacing the C-phenyl ring in its backbone with an indole or oxindole. In addition, it was possible to convert indole-modified tamoxifens to the corresponding 3,3'-bis(indolyl)methanes (BIMs) via an electrophilic substitution reaction with various benzaldehydes. We analyzed the anticancer potential of these indole-modified tamoxifens against various breast cancer cell lines and identified certain tamoxifen relatives with the potential to treat estrogen receptor (ER)-positive breast cancers, based on preliminary results of cell viability and caspase activity assays. The indole-modified tamoxifen BIM-Z,Z-35b, BIM-Z,Z-35f, and E-33 selectively reduced the viability of receptor-sensitive breast cancer cells more effectively than tamoxifen and suppressed the expression of ER-regulated genes. Moreover, Caspase-8 activity showed a specific increase in MCF-7 cells treated with these compounds. Our results indicate that these compounds may be an alternative to tamoxifen for the treatment of breast cancer.