Despite the widespread use of transition-metal catalysts in organic synthesis, transition-metal-catalyzed reactions of organosulfur compounds, which are known as catalyst poisons, have been difficult. In particular, the transition-metal-catalyzed addition of organosulfur compounds to unactivated alkenes remains a challenge. A novel gold-catalyzed hydrothiolation of unactivated alkenes is presented, which proceeds effectively to give the anti-Markovnikov-selective adducts in good yields and in a regioselective manner.

Ubiquinone and menaquinone play important roles in microbial respiratory chains. S. oneidensis is a facultative anaerobe, and it has been known that this microbe requires menaquinone (MK) and/or methylmenaquinone (MMK) to reduce inorganic and organic compounds, such as Fe(III), Mn(IV), fumarate, and nitrate, under anaerobic conditions. In this article, we show that voltammetry is useful to quantify ubiquinone (UQ), MK and MMK located in the cytoplasmic membrane simply by heating the microbe (thermal lysis) deposited on an indium-tin oxide electrode. It was found that the microbe predominantly produced UQ under aerobic conditions, while the production was switched to that of MMK under anaerobic conditions. This transition occurred at a dissolved oxygen concentration of ∼0.3 mg L −1 . It was also found in this study that the total quinone concentration (UQ + MK + MMK) in a single cell was constant at all stages of the culture in a nutrition broth, suggesting that the cytoplasmic membrane was saturated with the quinones. The reduction of Fe(III) citrate with S. oneidensis was also studied. It was found that this microbe decreased the UQ and MMK levels to 45% and 39% of the initial values, respectively, after finishing the reduction.

Despite the availability of selective synthetic approaches to multifunctionalized substituted olefins, the cyanothiolation of internal alkynes has been much less explored. Herein, we show that nonactivated internal alkynes can be successfully cyanothiolated with diaryl disulfides and tert-butyl isocyanide in the presence of a Pd catalyst (e.g., Pd(PPh)) with the release of isobutene and arenethiol to afford β-thiolated alkenyl cyanides in yields of 34-89%.

The highly regioselective hydroselenation of N-vinyl lactams has been revealed to successfully afford the corresponding N,Se-acetals as Markovnikov adducts. In the case of terminal N-vinyl lactams, Markovnikov-selective hydroselenation proceeds efficiently in the absence of any catalyst (or additive), owing to the acidity of the selenols. In contrast, the self-promoted hydroselenation is inefficient with internal N-vinyl lactams. In the presence of palladium diacetate (Pd(OAc)2), however, the desired hydroselenation of internal N-vinyl lactams proceeds efficiently to afford the corresponding N,Se-acetals.

Binary systems consisting of benzoyl peroxide (BPO) and diorganyl diselenide are effective in the selective benzoyloxyselenation of internal alkynes to afford the corresponding β-(benzoyloxy)alkenyl selenides in good yields. In contrast to internal alkynes, terminal alkynes undergo a novel C(sp)-H substitution with the phenylseleno group of the BPO/(PhSe) system, providing alkynyl selenides in good yields. Both selenation reactions might proceed via benzoyloxy selenide (PhC(O)O-SeAr) as a key intermediate for electrophilic addition to alkynes. The products alkenyl and alkynyl selenides are expected to be useful synthetic intermediates in organic synthesis.