Grubbs catalyst chloride

In the early syntheses of alkenyl alkylidene-mthenium catalysts, the first generation of Grubbs catalyst, it was observed that propargyl chloride could be a convenient source of the vinylcarbene initiator [53] with respect to the previous one arising from activation of cyclopropene [4] (Equation 8.3). In this synthesis the alkylidene hydrogen atom arises from the ruthenium hydride. 

Kevin J. Quinn of the College of the Holy Cross chose (Organic Lett. 2005, 7, 1243) a complementary approach in his synthesis of rollicosin. The symmetrical diol 4 is also available from carbohydrate precursors. Monosilylation followed by esterification with acryloyl chloride gave 5. Exposure of 5 to the Grubbs catalyst in the presence of 6 led, by ring-closing metathesis and cross metathesis, to the y-lactonc 7. Note that 5-lactone formation did not compete ... 

Upon treatment of (allylthio)vinylborane 172 with 1 mol% Grubbs catalyst, (GysPizfPhCHiRuCl 173, in methylene chloride, cychzation occurred smoothly to afford a 95% yie of the 2,5-dihydro-l,2-thiaborole 174 as shown in Scheme 17. The precursor 172 is itself readily available ttorn the reaction of allylthiol with diisopropylaminochloro-vmylborane 171 <20000M4935>. Essentially, the same reaction of allyloxyvinylborane 175 with 2% Gmbbs ... 

Heating of the alkynes 179 with ethyl vinyl ether and ethyl glyoxylate under microwave irradiation in the presence of the second-generation Grubbs catalyst 2 directly furnished a 2 1 mixture of the dihydropyrans 180 and 181 in a domino enyne CM/hetero-Diels-Alder process (Scheme 2.63) [36]. These mixtures could be readily equilibrated to give only the cis isomers 181 on treatment with zinc chloride in dichloromethane, subsequently. 

Subsequent addition of phenyl acetylene and styrene to the red solution containing A resulted in the isolation of the "Grubbs catalyst" [RuCl2(=CHPh)(P/Pr3)2] in moderate yields. However, when we first added an extra equivalent of hydrogen chloride to the hydride solution at -20 °C and subsequently added the acetylene and styrene, warmed the reaction mixture to room temperature and stirred it for an additional hour, the yield could be increased to 75%. 

Our first paper dealing with this problem, tried to answer the question how long should be the linker connecting both terminal positions of two subunits of sucrose We have found that minimum four carbon atom unit is able to connect the 6,6 -positions. Reaction of 13a with 1,4-di-iodobutane afforded macrocycle 39. Both terminal positions (C-6 and C-eQ could be also connected via the RCM approach which is shown in Scheme 9. Di-allyl derivative 40, easily prepared from diol 22, was converted into macrocycle 41 with the Grubbs catalyst. Alternatively, reaction of diol 22 with pentenoyl acid chloride afforded di-ester 42, which also underwent the RCM reaction to afford olefin 43. We were able to deprotect the sucrose backbone and obtain the corresponding free polyhydro)ylated macrocyclic derivatives (Scheme 9). 

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