N-Phenylselenophthalimide (N-PSP) and N-phenylselenosuccinimide (N-PSS). Two versatile carriers of the phenylseleno group. Oxyselenation of olefins and a selenium-based macrolide synthesis

Asymmetric Total Synthesis and Structure Confirmation of (+)-(3E)-Isolaurefucin Methyl Ether

“…Even though we were able to construct the isolaurefucin skeleton via the intramolecular epoxide opening route with decent stereoselectivity (3.6:1), we still wished to explore the direct synthesis of isolaurefucin methyl ether surrogate 4 via the projected novel organoselenium-mediated intramolecular alkoxyetherification of ,'-trans-,-unsaturated oxocene alcohol 7 in MeOH. In our synthesis of laurefucin (1), 9 we reported that exposure of ,'-cis-,-unsaturated oxocene alcohol 7' to excess N-phenylselenophthalimide (N-PSP) 18 In an experiment parallel to that of ,'-cis-,-unsaturated oxocene alcohol 7', subjection of ,'-trans-,-unsaturated alcohol 7 to the abovementioned comparable hydroxyetherification conditions gave rise to a 1:1 mixture (96% total yield) of the desired hydroxyl-ether 5 with an ,'-trans-2,8-dioxabicyclo[5.2.1]decane skeleton and bis-tetrahydrofuranyl alcohol 12. This latter presumably arises from attack at the C7 position of oxonium ion 8, and we were somewhat surprised that it was produced in such abundance.…”

Divergent Reactivity of 2‐Azetidinone‐Tethered Allenols with Electrophilic Reagents: Controlled Ring Expansion versus Spirocyclization

“…An initial validation of our hypothesis included the exposure of 2-azetidinonetethered allenol 1a to different sources of seleniranium ion, an attractive challenge from both synthetic and biological points of view. [7,15] After extensive experimentation, gratifyingly, we found that treatment of substrate 1a with the binary system consisting in an excess amount of NPSP (N-phenylselenophthalimide) [16] and catalytic amount of the Brønsted acid PTSA in dichloromethane at room temperature gave rise exclusively to the desired spirocyclic seleno-blactam 7a (Table 2). In the absence of PTSA, adduct 7a was obtained in lower yield.…”

Synthetic studies of roquefortine C: Synthesis of isoroquefortine C and a heterocycle

“…A two-step procedure developed by Danishefsky and coworkers (34,35) was then used for conversion of the resulting compound to the prenylated, tricyclic system. The first step of this sequence involves formation of a 3-selenenylated pyrroloindole (7a and 7b) by treatment with N-phenylselenophthalimide (36). This inseparable set of diastereomers then was treated with methyl triflate and prenyl tributylstannane to provide the alkylated compound (8).…”