NOVELTY - An optionally substituted precursor compound is treated with strongly basic compound, and isomerized, to obtain intermediate compound. The obtained compound is treated with oxidizing agent, to form bishalo-bisheteroaryl compound (A). The bishalo-bisheteroaryl compound is treated with organometallic compound, to form bismetallo-bisheteroaryl compound. The bismetallo-bisheteroaryl compound is reacted with electrophile, or bishalo-bisheteroaryl compound or bismetallo-bisheteroaryl compound with nucleophile, and Z group is introduced, to obtain fused tricyclic compound (I).    USE - Manufacture of fused tricyclic compound used for composition e.g. monomeric, oligomeric and polymeric materials for field-effect transistor (all claimed). Uses include but are not limited to solar cell, light-emitting diode, flat panel display, radio frequency identification card, electronic paper, sensor, photodetector and photovoltaic device.    ADVANTAGE - The fused tricyclic compound is manufactured efficiently and economically with excellent productivity. The composition containing fused tricyclic compound provides field-effect transistor with excellent workability.    DETAILED DESCRIPTION - An optionally substituted precursor compound having 5- or 6-membered heteroaryl ring with halogen at 1-position on heteroaryl ring, is treated with strongly basic compound, and isomerized, to obtain intermediate compound in which halogen atom is bonded to different position on the heteroaryl ring. The intermediate compound is treated with oxidizing agent, to form bishalo-bisheteroaryl compound of formula: Hal-HAr-HAr-Hal (A). The obtained bishalo-bisheteroaryl compound is optionally treated with organometallic compound such that metal is exchanged for halogen substituent, to form bismetallo-bisheteroaryl compound. The bismetallo-bisheteroaryl compound is reacted with suitable electrophile, or reacting bishalo-bisheteroaryl compound or bismetallo-bisheteroaryl compound with nucleophile, and Z group is introduced to the compound, to obtain fused tricyclic compound of formula (I). The fused tricyclic compound (I) is an acyl compound having heteroaryl ring(s) substituted with optionally protected acyl, or compound (I) is subjected to further reaction steps to form acyl compound in which both HAr moieties are substituted with optionally protected acyl.    Z=S, Se, NR5, C(O), C(O)C(O), Si(R5)2, SO, SO2, PR5, P(O)R5, BR5, C(R5)2, C=C(CN)2, or (C=C(CN2))2;    R5=1-50C organic group chosen from optionally substituted alkyl, perfluoroalkyl, aryl, and heteroaryl;    HAr=optionally substituted 5 or 6-membered heteroaryl ring;and    Hal=halo.    The compound does not include compound of formula (IIa).    R1=organic radical chosen from organic acyl compound having group of formula: -C(=O)-R11;    R11=aryl or heteroaryl optionally substituted with 1-10 halo, cyano, alkyl, perfluoroalkyl, acyl, alkoxy, or perfluoroalkoxy;    X=O, S, Se, or NR3;    R3=1-18C alkyl, perfluoroalkyl, aryl, or heteroaryl;    Y'=CH, CR4 or N;    R4=1-18C alkyl, aryl, or heteroaryl;    Z=S, Se, NR5, C(O), C(O)C(O), Si(R5)2, SO, SO2, PR5, P(O)R5, BR5, C(R5)2;and    R5=1-50C organic radical chosen from optionally substituted alkyl, perfluoroalkyl, aryl, or heteroaryl.    INDEPENDENT CLAIMS are included for the following:    (1) fused tricyclic compound, which is chosen from 48 compounds e.g. compounds of formulae (i)-(v); and    (2) composition, which contains compound of formula (XI)-(XIV).    a,a'=0 or 1;    R1',R2'=alkyl, fluoroalkyl, aryl, fluoroaryl, heteroaryl, arylalkyl, or heteroarylalkyl;    W',W"=heteroarylene group;    b,b'=0, 1, 2, 3, or 4;    c=1, 2, 3, or 4;    X',X"=O, S, Se, NR3', PR3', or Si(R3')2;    R3'=alkyl, heteroalkyl, or alkylaryl;    Y",Y"'=N, P, CH, CR4', or SiR4';    R4'=H, alkyl, fluoroalkyl, aryl, fluoroaryl or heteroaryl;    Z'=S, Se, NR5', C(O), C(O)C(O), Si(R5')2, SO, SO2, PR5', P(O)R5', BR5', C(R5')2 , C=C(CN)2, or (C=C(CN2))2;    R5'=1-50C organic radical chosen from optionally substituted alkyl, perfluoroalkyl, aryl and heteroaryl.