Scheme 4. Jins synthesis

26 % overall yield of both isomers from dialcohol 

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Jin and Weinreb reported the enantioselective total synthesis of 5,11-methano-morphanthridine Amaryllidaceae alkaloids via ethynylation of a chiral aldehyde followed by allenylsilane cyclization (Scheme 4.6) [10]. Addition of ethynylmagnesium bromide to 27 produced a 2 1 mixture of (S)- and (R)-propargyl alcohols 28. Both of these isomers were separately converted into the desired same acetate 28 by acetylation or Mitsunobu inversion reaction. After the reaction of 28 with a silyl cuprate, the resulting allene 29 was then converted into (-)-coccinine 31 via an allenylsilane cyclization. 

Qingwu Jin repeated Zawacki s synthesis but the overall yields to the macrocycle were too low to continue further studies.30 Jin developed another route that closed the macrocycle via Troger s base formation (Scheme 4). The Troger s base diol was used as a starting material. 

In 1996, Fuchs and Jin (85), continuing to exploit the chemistry of vinyl sulfones, reported a stereospecific synthesis of the azabicyclic ring system of the cephalotaxine ring by means of palladium(0)-mediated aminospiro-cyclization of tertiary allylic sulfones, as shown in Scheme 53. Treatment of compounds 305 and 306 with either triethylamine or tetramethylguanidine (TMG) in the presence of Pd(Ph3P)4 produced the spiro azabicycles 307 and 308, respectively. The tertiary allylic sulfone 309, under identical reaction conditions, yielded 310, which contains the A/CVD ring system of cephalotaxine. 

By employing ortho-(trimethylsilyl)aryl triflates as benzyne precursors, Jin and Yamamoto have reported the synthesis of indazoles under mild reaction conditions by the [3-1-2] cycloaddition of benzyne with diazomethane derivatives, followed by a 1,3-hydrogen shift (Scheme 12.54) [103]. Depending on the stoichiometry of the reagents and the reaction conditions, either 1-arylindazoles 194 or IH-inda-zoles 195 are readily produced in fair to good yields. 

The chemical fabrication scheme for Ag nanotriangles was adapted from work done by Jin and coworkers. The following chemicals were used silver nitrate, sodium citrate dihydrate, sodium borohydride, and bis(p-sulfonatophenyl) phenylphosphine dihydrate dipotassium salt (BSPP). Before beginning nanotriangle synthesis, all glassware was treated with aqua regia (3 1 HCkHNOs), rinsed thoroughly with ultrapure water (18.2... 

Jin and Kim reported the synthesis of polyamides coordinated to chromium tricarbonyl moieties (11) by condensation of (ii -phenylenediamine)Cr(CO)3 (12) with various diacid chlorides (13) (Scheme 2)7 It was noted that this polymer exhibited enhanced solubility due to incorporation of pendent chromium tricarbonyl moieties along its backbone. The viscosities of these polymers were determined in concentrated sulfuric acid or A(2/-dimethylacetamide containing 5% LiCl. The inherent viscosities of these metallated polymers ranged from 0.72 to 1.53 dL/g, and were found to be higher flian those of their organic analogs. 

The most elegant syntheses of rhododaurichromanic acid A 105a, B 105b, and of daurichromenic acid 113a were reported by Jin and coworkers [77]. Jin s synthesis features a unique microwave-assisted formal oxa-[3+3] cycloaddition of resorcinol derivatives with enals, and provides a rapid and novel approach to chromenes (Scheme 12.32). It also bypasses the DDQ aromatization that was problematic in ours [73] and in the synthesis of Wilson s [76]. Their... 

Poly(l,4-phenylenevinylene) (PPV) and its derivatives have been the subject of many studies on their structures and electrical, optical, and electroluminescence properties [113-115]. It is expected that the materials with donor and acceptor groups attached on a PPV backbone can maintain the poled state unrelaxed once properly poled, because PPV has a highly rigid backbone owing to its poly conjugated structure. A series of such types of polymers have been reported by Jin et al. [116]. The synthesis of one of these polymers (poly[ 2-methoxy-5-(2-(4-nitrophenyl)ethenyl)-l,4-phenyl-enevinylene -co-(l,4-phenylenevinylene)]) is shown in Scheme 5. The dy.y, of 4.2 pm V was obtained in the contact poled polymers. The SHG signal remained constant over a period of more than 1 month at room temperature. 

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