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                                                                      Exhibit 4d
                          COMMON STOCK PURCHASE WARRANT

Warrant No. _____________                               Number of Shares 400,000

                                  DYNAGEN, INC.


                           Void after January 22, 1999

         1.       Issuance. This Warrant is issued to LBI Group, Inc., by
              DynaGen, Inc. a corporation (hereinafter with its successors
              called the "Company").

         2.       Purchase Price: Number of Shares. Subject to the terms and
              conditions hereinafter set forth, the registered holder of this
              warrant (the "Holder"), commencing on the date hereof is entitled
              upon surrender of this Warrant with the subscription form annexed
              hereto duly executed at the office of the Company, 840 Memorial
              Drive, Cambridge, MA 02139, or such other office as the Company
              shall notify the Holder of in writing, to purchase from the
              Company at a price per share (the "Purchase Price") as follows,
              fully paid and nonassessable shares of Common Stock, $0.01 par
              value, of the Company (the "Common Stock"). Until such time as
              this Warrant is exercised in full or expires, the Purchase Price
              and the securities issuable upon exercise of this Warrant are
              subject to adjustment as hereinafter provided.

              The warrant shall vest as follows:

              A. Upon the execution of the Investment Banking Agreement, this
                 warrant is exercisable to purchase 200,000 shares at a price of
                 $0.125 per share.

              B. Upon extension of the subsequent three month periods, an
                 additional 200,000 shares at a price of $0.125 per share will 
                 be vested.

              C. If the Investment Banking Agreement is not extended by the
                 Company, in its sole discretion, the unvested warrant will be
                 canceled.

         3.       Payment of Purchase Price. The Purchase Price shall be paid in
              cash or by check.

         4.       Partial Exercise. This Warrant may be exercised in part, and
              the Holder shall be entitled to receive a new warrant, which shall
              be dated as of the date of this Warrant, covering the number of
              shares in respect of which this Warrant shall not have been
              exercised.

         5.       Issuance Date. The person or persons in whose name or names
              any certificate representing shares of Common Stock is issued
              hereunder shall be deemed to have become the holder of record of
              the shares represented thereby as at the close of 
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              business on the date this Warrant is exercised with respect to
              such shares, whether or not the transfer books of the Company
              shall be closed.

         6.       Expiration Date. This Warrant shall expire at the close of
              business on January 22, 1999, and shall be void thereafter.

         7.       Reserved Shares: Valid Issuance. The Company covenants that it
              will at all times from and after the date hereof reserve and keep
              available such number of its authorized shares of Common Stock
              free from all preemptive or similar rights therein, as will be
              sufficient to permit the exercise of this Warrant in full. The
              Company further covenants that such shares as may be issued
              pursuant to the exercise of this Warrant will, upon issuance, be
              duly and validly issued, fully paid and nonassessable and free
              from all taxes, liens and charges with respect to the issuance
              thereof.

         8.       Dividends. If after the date hereof the Company shall
              subdivide the Common Stock by split-up or otherwise or combine the
              Common Stock or issue additional shares of Common Stock in payment
              of a stock dividend on the Common Stock, the number of shares
              issuable on the exercise of this Warrant shall forthwith be
              proportionately increased in the case of a subdivision or stock
              dividend, or proportionately decreased in the case of a
              combination, and the Purchase Price shall forthwith be
              proportionately decreased in the case of a subdivision or stock
              dividend, or proportionately increased in the case of a
              combination.

         9.       Mergers and Reclassifications. If after the date hereof there
              shall be any reclassification, capital reorganization or change of
              the Common Stock (other than a result of a subdivision,
              combination or stock dividend provided for in Section 8 hereof),
              or any consolidation of the Company with, or merger of the Company
              unto, another corporation or other business organization (other
              than a consolidation or merger in which the Company is the
              continuing corporation and which does not result in any
              reclassification or change of the outstanding Common Stock), or
              any sale or conveyance to another corporation or other business
              organization of all or substantially all of the assets of the
              Company, then, as a condition of such reclassification,
              reorganization, change, consolidation, merger, sale or conveyance,
              lawful provisions shall be made, and duly executed documents
              evidencing the same from the Company or its successor shall be
              delivered to the Holder, so that the Holder shall thereafter have
              the right to purchase, at a total price not to exceed that payable
              upon the exercise of this Warrant in full, the kind and amount of
              shares of stock and other securities and property receivable upon
              such reclassification, reorganization, change, consolidation,
              merger, sale or conveyance by a Holder of the number of shares of
              Common Stock which might have been purchased by the Holder
              immediately prior to such reclassification, reorganization,
              change, consolidation, merger, sale or conveyance, and in any such
              case appropriate provisions shall be made with respect to the
              rights and interest of the Holder to the end that the provisions
              hereof (including without limitation provisions for the adjustment
              of the 


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              Purchase Price and the number of shares issuable hereunder) shall
              thereafter be applicable in relation to any shares of stock or
              other securities and property thereafter deliverable upon exercise
              hereof.

         10.      Fractional Shares. In no event shall any fractional share of
              Common Stock be issued upon any exercise of this Warrant. If, upon
              exercise of this Warrant as an entirety, the Holder would, except
              as provided in this Section 10, be entitled to receive a
              fractional share of Common Stock, then the Company shall issue the
              next higher number of full shares of Common Stock, issuing a full
              share with respect to such fractional share.

         11.      Certificate of Adjustment. Whenever the Purchase Price is
              adjusted, as herein provided, the Company shall promptly deliver
              to the Holder a certificate of a firm of independent public
              accounts setting forth the Purchase Price after such adjustment
              and setting forth a brief statement of the facts requiring such
              adjustment.

         12.      Notice of Record Dates, Etc. In the event of:

         (a)  any taking by the Company of a record of the holder of any class 
of securities or the purpose of determining the holders thereof who are entitled
to receive any dividend or other distribution, or any right to subscribe for,
purchase or otherwise acquire any shares of stock for any class or any other
securities or property, or to receive any other right.

         (b)  any reclassification of the capital stock of the Company, capital
reorganization of the Company, consolidation or merger involving the Company, or
sale conveyance of all or substantially all of its assets, or

         (c)  any voluntary or involuntary dissolution, liquidation or 
winding-up of the Company.

then and in each such event the Company will mail or cause to be mailed to the
Holder a notice specifying (i) the date on which any such record is to be taken
for the purpose of such dividend, distribution or right, and stating the amount
of character of such dividend, distribution or right, or (ii) the date on which
any such reclassification, reorganization, consolidation, merger, sale or
conveyance, dissolution, liquidation or winding-up is take place, and the time,
if any is to be fixed, as of which the holders of record in respect of such
event are to be determined. Such notice shall be mailed at least 20 days prior
to the date specified in such notice on which any action is to be taken.

         13.      Amendment. The terms of this Warrant may be amended, modified
              or waived only with the written consent of the Company and the
              holders of Warrants representing at least two thirds of the number
              of shares of Common Stock then issuable upon the exercise of the
              Warrants. No such amendment, modification or waiver shall be
              effective as to this Warrant unless the terms of such amendment,
              modification or waiver shall apply with the same force and effect
              to all of the other Warrants then outstanding.


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         14.      Warrant Register, Transfers, Etc.

         A.   The Company will maintain a register containing the names and
addresses of the registered holders of the Warrants. The Holder may change its
address as shown on the warrant register by written notice to the Company
requesting such change. Any notice or written communication required or
permitted to be given to the Holder may be given by certified mail or delivered
to the Holder at its address as shown on the warrant register.

         B.   Subject to compliance with applicable federal and state securities
laws, this Warrant may be transferred by the Holder with respect to any or all
of the shares purchasable hereunder. Upon surrender of this Warrant to the
Company, together with the assignment hereof properly endorsed, for transfer of
this Warrant as an entirety by the Holder, the Company shall issue a new warrant
of the same denomination to the assignee. Upon surrender of this Warrant to the
Company, together with the assignment hereof properly endorsed, by the Holder
for transfer with respect to a portion of the shares of Common Stock
purchasable hereunder, the Company shall issue a new warrant to the assignee,
in such denomination as shall be requested by the Holder hereof, and shall issue
to such Holder a new warrant covering the number of shares in respect of which
this Warrant shall not have been transferred.

         C.   In case this Warrant shall be mutilated, lost, stolen or 
destroyed, the Company shall issue a new warrant of like tenor and denomination
and deliver the same (i) in exchange and substitution for and upon surrender and
cancellation of any mutilated Warrant, or (ii) in lieu of any Warrant lost,
stolen or destroyed, upon receipt of evidence reasonably satisfactory to the
Company of the loss, theft or destruction of such Warrant (including a
reasonably detailed affidavit with respect to the circumstances of any loss,
theft or destruction) and of indemnity reasonably satisfactory to the Company,
provided, however, that so long as Richmond Capital is the registered holder of
this Warrant, no indemnity shall be required other than it written agreement to
indemnify the Company against any loss arising from the issuance of such new
warrant.

         15.      No Impairment. The Company will not, by amendment of its
              by-laws or through any reclassification, capital reorganization,
              consolidation, merger, sale or conveyance of assets, dissolution,
              liquidation, issue or sale of securities or any other voluntary
              action avoid or seek to avoid the observance or performance of any
              of the terms of this Warrant, but will at all times in good faith
              assist in the carrying out of all such terms and in the taking of
              all such action as may be necessary or appropriate in order to
              protect the rights of the Holder.

         16.      Governing Law. The provisions and terms of this Warrant shall
              be governed by and construed in accordance with the internal laws
              of the Commonwealth of Massachusetts.


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